├── _config.yml ├── practise1 ├── prog6.sh ├── prog1.sh ├── prog2.sh ├── prog3.sh ├── prog5.sh ├── prog7.sh ├── prog4.sh ├── prog9.sh ├── prog10.sh ├── prog8.sh └── README.md ├── first ├── first.sh └── python.py ├── variable ├── test1.sh ├── name.sh ├── name2.sh ├── comd.sh └── comd2.sh ├── exit-status ├── error.sh ├── and.sh ├── or.sh ├── ping.sh └── exitCode.sh ├── debugging ├── xtrace.sh └── set.sh ├── bash.png ├── README.pdf ├── README-image.png ├── stdin └── stdin.sh ├── functions ├── call.sh ├── greet2.sh └── greet.sh ├── loops ├── color.sh ├── color2.sh ├── read.sh ├── natur.sh ├── user.sh └── picture.sh ├── pos-param ├── pos2.sh └── pos1.sh ├── ifElse ├── ifStat.sh ├── ifElse.sh ├── ifElif.sh └── case.sh ├── practise2 ├── README.md └── outText.txt ├── CODE_OF_CONDUCT.md ├── README.md └── LICENSE /_config.yml: -------------------------------------------------------------------------------- 1 | theme: jekyll-theme-hacker -------------------------------------------------------------------------------- /practise1/prog6.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | file $1 -------------------------------------------------------------------------------- /first/first.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | echo "My First Script!" -------------------------------------------------------------------------------- /practise1/prog1.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | echo "Hello World!" -------------------------------------------------------------------------------- /variable/test1.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | [ -e /etc/passwd ] 3 | -------------------------------------------------------------------------------- /exit-status/error.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | ls /randomDirectory 3 | echo "$?" -------------------------------------------------------------------------------- /first/python.py: -------------------------------------------------------------------------------- 1 | #!/usr/bin/python 2 | print "This is a python script!" -------------------------------------------------------------------------------- /debugging/xtrace.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash-x 2 | VALUE="Hello World!" 3 | echo "$VALUE" -------------------------------------------------------------------------------- /practise1/prog2.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | MY_VAR="Hello World!" 3 | echo "$MY_VAR" -------------------------------------------------------------------------------- /practise1/prog3.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | DATE=$(date) 3 | echo "Today is: ${DATE}" -------------------------------------------------------------------------------- /bash.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/MadhavBahl/shebang-everything/HEAD/bash.png -------------------------------------------------------------------------------- /README.pdf: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/MadhavBahl/shebang-everything/HEAD/README.pdf -------------------------------------------------------------------------------- /variable/name.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | MY_NAME="Madhav Bahl" 3 | echo "Hello, I am $MY_NAME" -------------------------------------------------------------------------------- /variable/name2.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | MY_NAME="Madhav Bahl" 3 | echo "Hello, I am ${MY_NAME}" -------------------------------------------------------------------------------- /README-image.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/MadhavBahl/shebang-everything/HEAD/README-image.png -------------------------------------------------------------------------------- /practise1/prog5.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | for (( i=1;i<=10;i++ )) 3 | do 4 | echo "Number $i" 5 | done -------------------------------------------------------------------------------- /practise1/prog7.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | echo "This script will return an exit status 200" 3 | exit 200 -------------------------------------------------------------------------------- /stdin/stdin.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | read -p "Please Enter You Name: " NAME 3 | echo "Your Name Is: $NAME" -------------------------------------------------------------------------------- /variable/comd.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | SERVER_NAME=`hostname` 3 | echo "This script is being run on ${SERVER_NAME}" -------------------------------------------------------------------------------- /functions/call.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | function myFunc () { 3 | echo "Shell Scripting Is Fun!" 4 | } 5 | myFunc -------------------------------------------------------------------------------- /loops/color.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | for COLOR in red green blue 3 | do 4 | echo "The Color is: ${COLOR}" 5 | done -------------------------------------------------------------------------------- /loops/color2.sh: -------------------------------------------------------------------------------- 1 | COLORS="red green blue" 2 | for COLOR in $COLORS 3 | do 4 | echo "The Color is: ${COLOR}" 5 | done -------------------------------------------------------------------------------- /variable/comd2.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | CONTENTS=$(ls) 3 | echo "The contents of this directory are: " 4 | echo "$CONTENTS" -------------------------------------------------------------------------------- /pos-param/pos2.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | echo "Running script: $0" 3 | for PARAM in $@ 4 | do 5 | echo "Parameter: $PARAM" 6 | done -------------------------------------------------------------------------------- /ifElse/ifStat.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | SHELL_NAME="bash" 3 | 4 | if [ "$SHELL_NAME" = "bash" ] 5 | then 6 | echo "You are using bash shell" 7 | fi -------------------------------------------------------------------------------- /loops/read.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | LINE=1 3 | while read CURRENT_LINE 4 | do 5 | echo "${LINE}: $CURRENT_LINE" 6 | ((LINE++)) 7 | done < /etc/passwd -------------------------------------------------------------------------------- /loops/natur.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | INDEX=1 3 | while [ $INDEX -lt 11 ] 4 | do 5 | echo "Current Number: ${INDEX}" 6 | (( INDEX = INDEX + 1 )) 7 | done -------------------------------------------------------------------------------- /practise1/prog4.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | if [ -e /random ] 3 | then 4 | echo "Yes, /random exists!" 5 | else 6 | echo "No, /random does not exists!" 7 | fi -------------------------------------------------------------------------------- /exit-status/and.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | MY_VAR=10 3 | if [ "$MY_VAR" -ge 5 ] && [ "$MY_VAR" -le 15 ] 4 | then 5 | echo "Given variable is within the range" 6 | fi -------------------------------------------------------------------------------- /loops/user.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | while [ "$CORRECT" != y ] 3 | do 4 | read -p "Enter your username: " USERNAME 5 | read -p "Is $USERNAME correct? " CORRECT 6 | done -------------------------------------------------------------------------------- /pos-param/pos1.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | echo "Running script: $0" 3 | echo "Parameter 1: $1" 4 | echo "Parameter 2: $2" 5 | echo "Parameter 3: $3" 6 | echo "Parameter 4: $4" -------------------------------------------------------------------------------- /exit-status/or.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | MY_VAR=10 3 | if [ "$MY_VAR" -ge 15 ] || [ "$MY_VAR" -le 11 ] 4 | then 5 | echo "Given variable is either greater than 15 or less than 11" 6 | fi -------------------------------------------------------------------------------- /practise1/prog9.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | cat /etc/shadow 3 | STATUS=$? 4 | if [ STATUS == 0 ] 5 | then 6 | echo "Command Executed!" 7 | else 8 | echo "Command Not Executed!" 9 | fi -------------------------------------------------------------------------------- /functions/greet2.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | function greetings() { 3 | for PERSON_NAME in $@ 4 | do 5 | echo "Hello ${PERSON_NAME}" 6 | done 7 | } 8 | greetings World! Random Guy Stranger -------------------------------------------------------------------------------- /loops/picture.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | PICTURES=$(ls *.jpg) 3 | NEW="new" 4 | for PICTURE in $PICTURES 5 | do 6 | echo "Renaming $PICTURE to new-$PICTURE" 7 | mv $PICTURE $NEW-$PICTURE 8 | done -------------------------------------------------------------------------------- /practise1/prog10.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | function fileCount () { 3 | LOC=$1 4 | ls $LOC > outText.txt 5 | NUM_FILES=$(wc -w outText.txt) 6 | echo $NUM_FILES 7 | } 8 | fileCount /etc -------------------------------------------------------------------------------- /debugging/set.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | echo "Turning x-trace on!" 3 | set -x 4 | VAL="Hello World!" 5 | echo "$VAL" 6 | set +x 7 | VAL="x-trace turned off!" 8 | echo "Turning x-trace off!" 9 | echo "$VAL" -------------------------------------------------------------------------------- /ifElse/ifElse.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | SHELL_NAME="bash" 3 | 4 | if [ "$SHELL_NAME" = "bash" ] 5 | then 6 | echo "You are using bash shell" 7 | else 8 | echo "You are not using the bash shell" 9 | fi -------------------------------------------------------------------------------- /functions/greet.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | function greetings() { 3 | USER=$(whoami) 4 | echo "Welcome ${USER}" 5 | currentTime 6 | } 7 | function currentTime() { 8 | echo "Current Time Is: $(date +%r)" 9 | } 10 | greetings -------------------------------------------------------------------------------- /exit-status/ping.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | HOST="google.com" 3 | ping -c 1 $HOST # -c is used for count, it will send the request, number of times mentioned 4 | if [ "$?" -eq "0" ] 5 | then 6 | echo "$HOST reachable" 7 | else 8 | echo "$HOST unreachable" 9 | fi -------------------------------------------------------------------------------- /practise1/prog8.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | DIR_NAME="$1" 3 | if [ -e $DIR_NAME ] 4 | then 5 | echo "The given file/directory exists!" 6 | exit 0 7 | fi 8 | echo "The given path to directory does not exists!" 9 | mkdir $DIR_NAME 10 | echo "Directory created!" 11 | exit 1 -------------------------------------------------------------------------------- /ifElse/ifElif.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | SHELL_NAME="bash" 3 | 4 | if [ "$SHELL_NAME" = "bash" ] 5 | then 6 | echo "You are using bash shell" 7 | elif [ "$SHELL_NAME" = "csh" ] 8 | then 9 | echo "You are using csh shell" 10 | else 11 | echo "You are not using the bash or csh shell" 12 | fi -------------------------------------------------------------------------------- /ifElse/case.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | read -p "Enter the answer in Y/N: " ANSWER 3 | case "$ANSWER" in 4 | [yY] | [yY][eE][sS]) 5 | echo "The Answer is Yes :)" 6 | ;; 7 | [nN] | [nN][oO]) 8 | echo "The Answer is No :(" 9 | ;; 10 | *) 11 | echo "Invalid Answer :/" 12 | ;; 13 | esac -------------------------------------------------------------------------------- /exit-status/exitCode.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | DIR_NAME="/home/madhav/Desktop/Play" 3 | if [ -e $DIR_NAME ] 4 | then 5 | echo "Given Directory Already Exists" 6 | echo "Moving into ${DIR_NAME}" 7 | cd $DIR_NAME 8 | exit 0 9 | fi 10 | echo "Given Directory Does Not Exists" 11 | mkdir $DIR_NAME 12 | cd $DIR_NAME 13 | exit 1 -------------------------------------------------------------------------------- /practise2/README.md: -------------------------------------------------------------------------------- 1 | # Shebang-Everything 2 | 3 | Your unofficial guidebook to shell programming 4 | 5 | ## Programs for practise-2 6 | 7 | Write scripts for following programs yourself, if you are not able to solve them you can see the code. 8 | 9 | ### Program 1 10 | 11 | Write a shell script that prints "This script will return an exit status 200" and make sure that the script does return with an exit status 200. 12 | 13 | [See the code here!](./prog1.sh) 14 | 15 | ### Program 2 16 | 17 | Write a shell script that accepts the absolute path to a file or directory as an argument, and if that file/dir exists, it returns with 0 exit status. Else, it makes creates that directory and then return with code 1. 18 | 19 | [See the code here!](./prog2.sh) 20 | 21 | ### Program 3 22 | 23 | Write a script that executes the command "cat /etc/shadow". If the command returns a 0 exit 24 | status report "Command Executed!" and exit with a 0 exit status. If the command returns a 25 | non­zero exit status report "Command Not Executed!" and exit with a 1 exit status. 26 | 27 | [See the code here!](./prog3.sh) 28 | 29 | ### Program 4 30 | 31 | Write a function in shell script to take a path as arguement and print the number of files/directories in that path. 32 | 33 | **Hint** You can try copying the output of ls command in a text file and then count the number of lines in that file. 34 | 35 | [See the code here!](./prog4.sh) -------------------------------------------------------------------------------- /practise1/README.md: -------------------------------------------------------------------------------- 1 | # Shebang-Everything 2 | 3 | Your unofficial guidebook to shell programming 4 | 5 | ## Programs for practise 6 | 7 | Write scripts for following programs yourself, if you are not able to solve them you can see the code. 8 | 9 | ### Program 1 10 | 11 | Write a shell script that prints "Hello World!" to the screen. 12 | 13 | [See the code here!](./prog1.sh) 14 | 15 | ### Program 2 16 | 17 | Assign some message to a variable and display that variable to screen. 18 | 19 | [See the code here!](./prog2.sh) 20 | 21 | ### Program 3 22 | 23 | Store the value of `date` command in a variable and display the message "Today is: _______" where, `_____` represents output of `date` command. 24 | 25 | [See the code here!](./prog3.sh) 26 | 27 | ### Program 4 28 | 29 | Check whether /random exists. 30 | 31 | [See the code here!](./prog4.sh) 32 | 33 | ### Program 5 34 | 35 | Write a program to print your 5 favourite fruits. 36 | 37 | [See the code here!](./prog5.sh) 38 | 39 | ### Program 6 40 | 41 | Write a program to take address of file as arguement and then check the file type. 42 | (Hint! use file command) 43 | 44 | [See the code here!](./prog6.sh) 45 | 46 | ### Program 7 47 | 48 | Write a shell script that prints "This script will return an exit status 200" and make sure that the script does return with an exit status 200. 49 | 50 | [See the code here!](./prog7.sh) 51 | 52 | ### Program 8 53 | 54 | Write a shell script that accepts the absolute path to a file or directory as an argument, and if that file/dir exists, it returns with 0 exit status. Else, it makes creates that directory and then return with code 1. 55 | 56 | [See the code here!](./prog8.sh) 57 | 58 | ### Program 9 59 | 60 | Write a script that executes the command "cat /etc/shadow". If the command returns a 0 exit 61 | status report "Command Executed!" and exit with a 0 exit status. If the command returns a 62 | non­zero exit status report "Command Not Executed!" and exit with a 1 exit status. 63 | 64 | [See the code here!](./prog9.sh) 65 | 66 | ### Program 10 67 | 68 | Write a function in shell script to take a path as arguement and print the number of files/directories in that path. 69 | 70 | **Hint** You can try copying the output of ls command in a text file and then count the number of lines in that file. 71 | 72 | [See the code here!](./prog10.sh) 73 | -------------------------------------------------------------------------------- /CODE_OF_CONDUCT.md: -------------------------------------------------------------------------------- 1 | # Contributor Covenant Code of Conduct 2 | 3 | ## Our Pledge 4 | 5 | In the interest of fostering an open and welcoming environment, we as contributors and maintainers pledge to making participation in our project and our community a harassment-free experience for everyone, regardless of age, body size, disability, ethnicity, gender identity and expression, level of experience, nationality, personal appearance, race, religion, or sexual identity and orientation. 6 | 7 | ## Our Standards 8 | 9 | Examples of behavior that contributes to creating a positive environment include: 10 | 11 | * Using welcoming and inclusive language 12 | * Being respectful of differing viewpoints and experiences 13 | * Gracefully accepting constructive criticism 14 | * Focusing on what is best for the community 15 | * Showing empathy towards other community members 16 | 17 | Examples of unacceptable behavior by participants include: 18 | 19 | * The use of sexualized language or imagery and unwelcome sexual attention or advances 20 | * Trolling, insulting/derogatory comments, and personal or political attacks 21 | * Public or private harassment 22 | * Publishing others' private information, such as a physical or electronic address, without explicit permission 23 | * Other conduct which could reasonably be considered inappropriate in a professional setting 24 | 25 | ## Our Responsibilities 26 | 27 | Project maintainers are responsible for clarifying the standards of acceptable behavior and are expected to take appropriate and fair corrective action in response to any instances of unacceptable behavior. 28 | 29 | Project maintainers have the right and responsibility to remove, edit, or reject comments, commits, code, wiki edits, issues, and other contributions that are not aligned to this Code of Conduct, or to ban temporarily or permanently any contributor for other behaviors that they deem inappropriate, threatening, offensive, or harmful. 30 | 31 | ## Scope 32 | 33 | This Code of Conduct applies both within project spaces and in public spaces when an individual is representing the project or its community. Examples of representing a project or community include using an official project e-mail address, posting via an official social media account, or acting as an appointed representative at an online or offline event. Representation of a project may be further defined and clarified by project maintainers. 34 | 35 | ## Enforcement 36 | 37 | Instances of abusive, harassing, or otherwise unacceptable behavior may be reported by contacting the project team at madhavbahl10@gmail.com. The project team will review and investigate all complaints, and will respond in a way that it deems appropriate to the circumstances. The project team is obligated to maintain confidentiality with regard to the reporter of an incident. Further details of specific enforcement policies may be posted separately. 38 | 39 | Project maintainers who do not follow or enforce the Code of Conduct in good faith may face temporary or permanent repercussions as determined by other members of the project's leadership. 40 | 41 | ## Attribution 42 | 43 | This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 1.4, available at [http://contributor-covenant.org/version/1/4][version] 44 | 45 | [homepage]: http://contributor-covenant.org 46 | [version]: http://contributor-covenant.org/version/1/4/ 47 | -------------------------------------------------------------------------------- /practise2/outText.txt: -------------------------------------------------------------------------------- 1 | acpi 2 | adduser.conf 3 | alternatives 4 | anacrontab 5 | apache2 6 | apg.conf 7 | apm 8 | apparmor 9 | apparmor.d 10 | apport 11 | appstream.conf 12 | apt 13 | aptdaemon 14 | at-spi2 15 | avahi 16 | bash.bashrc 17 | bash_completion 18 | bash_completion.d 19 | bindresvport.blacklist 20 | binfmt.d 21 | bluetooth 22 | brlapi.key 23 | brltty 24 | brltty.conf 25 | ca-certificates 26 | ca-certificates.conf 27 | ca-certificates.conf.dpkg-old 28 | calendar 29 | chatscripts 30 | chromium-browser 31 | compizconfig 32 | console-setup 33 | cracklib 34 | cron.d 35 | cron.daily 36 | cron.hourly 37 | cron.monthly 38 | crontab 39 | cron.weekly 40 | cups 41 | cupshelpers 42 | dbus-1 43 | dconf 44 | debconf.conf 45 | debian_version 46 | default 47 | deluser.conf 48 | depmod.d 49 | dhcp 50 | dictionaries-common 51 | dnsmasq.d 52 | doc-base 53 | dpkg 54 | drirc 55 | emacs 56 | environment 57 | ffserver.conf 58 | firefox 59 | fonts 60 | fstab 61 | fuse.conf 62 | fwupd.conf 63 | gai.conf 64 | gamin 65 | gconf 66 | gdb 67 | gftp 68 | ghostscript 69 | gimp 70 | gnome 71 | gnome-app-install 72 | groff 73 | group 74 | group- 75 | grub.d 76 | gshadow 77 | gshadow- 78 | gss 79 | gtk-2.0 80 | gtk-3.0 81 | guest-session 82 | hdparm.conf 83 | host.conf 84 | hostname 85 | hosts 86 | hosts.allow 87 | hosts.deny 88 | hp 89 | ifplugd 90 | iftab 91 | ImageMagick-6 92 | init 93 | init.d 94 | initramfs-tools 95 | inputrc 96 | insserv 97 | insserv.conf 98 | insserv.conf.d 99 | iproute2 100 | issue 101 | issue.net 102 | kbd 103 | kernel 104 | kernel-img.conf 105 | kerneloops.conf 106 | ldap 107 | ld.so.cache 108 | ld.so.conf 109 | ld.so.conf.d 110 | legal 111 | libao.conf 112 | libaudit.conf 113 | libnl-3 114 | libpaper.d 115 | libreoffice 116 | lightdm 117 | lighttpd 118 | lintianrc 119 | locale.alias 120 | locale.gen 121 | localtime 122 | logcheck 123 | login.defs 124 | logrotate.conf 125 | logrotate.d 126 | lsb-release 127 | ltrace.conf 128 | machine-id 129 | magic 130 | magic.mime 131 | mailcap 132 | mailcap.order 133 | manpath.config 134 | mime.types 135 | mke2fs.conf 136 | modprobe.d 137 | modules 138 | modules-load.d 139 | mtab 140 | mtools.conf 141 | nanorc 142 | network 143 | NetworkManager 144 | networks 145 | newt 146 | nsswitch.conf 147 | openal 148 | opt 149 | os-release 150 | pam.conf 151 | pam.d 152 | papersize 153 | passwd 154 | passwd- 155 | pcmcia 156 | perl 157 | php 158 | pki 159 | pm 160 | pnm2ppa.conf 161 | polkit-1 162 | popularity-contest.conf 163 | ppp 164 | printcap 165 | profile 166 | profile.d 167 | protocols 168 | pulse 169 | python 170 | python2.7 171 | python3 172 | python3.5 173 | python3.6 174 | rc0.d 175 | rc1.d 176 | rc2.d 177 | rc3.d 178 | rc4.d 179 | rc5.d 180 | rc6.d 181 | rc.local 182 | rcS.d 183 | redis 184 | resolvconf 185 | resolv.conf 186 | rmt 187 | rpc 188 | rsyslog.conf 189 | rsyslog.d 190 | samba 191 | sane.d 192 | securetty 193 | security 194 | selinux 195 | sensors3.conf 196 | sensors.d 197 | services 198 | sgml 199 | shadow 200 | shadow- 201 | shells 202 | signond.conf 203 | signon-ui 204 | skel 205 | speech-dispatcher 206 | ssh 207 | ssl 208 | subgid 209 | subgid- 210 | subuid 211 | subuid- 212 | sudoers 213 | sudoers.d 214 | sysctl.conf 215 | sysctl.d 216 | systemd 217 | teamviewer 218 | terminfo 219 | thermald 220 | thunderbird 221 | timezone 222 | tmpfiles.d 223 | ucf.conf 224 | udev 225 | udisks2 226 | ufw 227 | updatedb.conf 228 | update-manager 229 | update-motd.d 230 | update-notifier 231 | UPower 232 | upstart-xsessions 233 | usb_modeswitch.conf 234 | usb_modeswitch.d 235 | vbox 236 | vdpau_wrapper.cfg 237 | vim 238 | vtrgb 239 | wgetrc 240 | wpa_supplicant 241 | X11 242 | xdg 243 | xml 244 | yum 245 | zsh_command_not_found 246 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # Shell Scripting 2 | 3 | A shell script is a computer program designed to be run by the Unix shell, a command-line interpreter. 4 | Use this guide to get a great hold on shell scripting! 5 | 6 | 10 | 11 | 12 | 13 | ## Index Of Contents 14 | 15 | 1. [Introduction to scripts](#scripts) 16 | 2. [Our first script](#our-first-script) 17 | 3. [Variables](#variables) 18 | 1. [Syntax](#syntax-for-variables) 19 | 2. [Examples](#examples-of-variables) 20 | 3. [Valid Variable Names](#variable-names) 21 | 4. [Tests](#tests) 22 | 1. [Syntax](#syntax-for-tests) 23 | 2. [File Operations](#file-test-operations) 24 | 3. [String Operations](#string-test-operations) 25 | 4. [Arithmetic Operations](#arithmetic-operators) 26 | 5. [Making Decisions Based On Conditions](#making-decisions) 27 | 1. [The IF Statement](#the-if-statement) 28 | * [Syntax for IF Statement](#the-if-statement) 29 | * [IF-Else Tree](#if-else-tree) 30 | * [IF-Elif-Else Ladder](#if-elif-ladder) 31 | 2. [Case statements](#case-statements) 32 | * [Syntax for case statements](#case-satements) 33 | * [When to use case statements](#when-to-use) 34 | 6. [Iterative Statements](#iterative-statements) 35 | 1. [The For loop](#for-loop) 36 | 2. [The While loop](#while-loop) 37 | 3. [Infinite loop](#infinite-loop) 38 | 4. [Examples](#example:-print-first-10-natural-numbers) 39 | 5. [The continue statement](#the-continue-statement) 40 | 6. [The break statement](#the-break-statement) 41 | 7. [Positional Parameters](#positional-parameters) 42 | 8. [Exit Statuses](#exit-status) 43 | 1. [Logical Operations](#logic-operations) 44 | 2. [The Semicolon](#the-semicolon) 45 | 3. [The Exit Command](#the-exit-command) 46 | 9. [Functions in shell](#functions) 47 | 1. [Syntax for creating functions](#functions) 48 | 2. [Calling a function from another function](#calling-a-function-from-another-function) 49 | 3. [Positional Parameters In Functions](#positional-parameters-in-functions) 50 | 4. [Scope of a variable](#variable-scope) 51 | 5. [Return codes for function](#return-codes-for-function) 52 | 10. [Wildcards](#wildcards) 53 | 1. [What are wildcards](#wildcards) 54 | 2. [Some Commonly Used Wildcards](#some-commonly-used-wildcards) 55 | 3. [Predefined named character classes](#predefined-named-character-classes) 56 | 4. [Using wildcards in shell scripts](#using-wildcards-in-shell-scripts) 57 | 11. [Logging](#logging) 58 | 1. [Syslog](#syslog) 59 | 2. [Facilities](#facilities) 60 | 3. [Severities](#severities) 61 | 4. [The Logger Command](#the-logger-command) 62 | 12. [Debugging](#debugging) 63 | 13. [Sample Programs For Revision](#some-sample-programs) 64 | 14. [Download free PDF](#downloadable-pdf) 65 | 66 | ## Scripts 67 | 68 | You might have came across the word 'script' a lot of times, but what is the meaning of a script?
69 | So basically, a script is a command line program that contains a series of commands to be executed. These commands are execued by an interpreter.
70 | Anything you can put into a command line, you can put in a script. And, scripts are great for automating tasks. 71 | If you find yourself repeating some commands frequently, you can, rather you should, create a script for doing it! 72 | 73 | ## Our first script 74 | 75 | ```sh 76 | #!/bin/bash 77 | echo "My First Script!" 78 | ``` 79 | 80 | To run it: 81 | 82 | ``` 83 | $ chmod 755 script.sh 84 | $ ./script.sh 85 | ``` 86 | 87 | [Find the code here](./first/first.sh) 88 | 89 | ## Shebang 90 | 91 | A script starts with #! __Path To Bash__ 92 | 93 | `#` is often called sharp and `!` is called Bang, hence the name sharp bang, but generally people say it **shebang** instead of sharp bang. 94 | 95 | ### Comments 96 | 97 | Comments are started by a `#` sign, anything after pound sign on that line is ignored. 98 | 99 | #### Example 100 | ```sh 101 | #!/bin/bash 102 | echo "Hello World!" 103 | # This line won be executed! 104 | ``` 105 | 106 | **Basic Examples Of Shell Scripts** 107 | 108 | - Using csh as interpreter 109 | 110 | ```sh 111 | #!/bin/csh 112 | echo "This script uses csh as the interpreter!" 113 | ``` 114 | 115 | - Using ksh as interpreter 116 | 117 | ```sh 118 | #!/bin/ksh 119 | echo "This script uses ksh as the interpreter!" 120 | ``` 121 | 122 | - Using zsh as interpreter 123 | 124 | ```sh 125 | #!/bin/zsh 126 | echo "This script uses zsh as the interpreter!" 127 | ``` 128 | 129 | ### Use it or not? 130 | 131 | If a script does not contain the shebang, the commands are executed using your shell, so there are chances that the code might run properly, but still, that isn't the correct way of doing it!
132 | Different shells have slightly varying syntax. 133 |
134 | 135 | **More than just shell scripts!**
136 | 137 | You dont have to use shell as the interpreter for your scripts. For example, you can run a python script too by supplying the path in shebang. 138 | 139 | ```sh 140 | #!/usr/bin/python 141 | print "This is a python script!" 142 | ``` 143 | 144 | To run it: 145 | 146 | ``` 147 | $ chmod 755 name.py 148 | $ ./name.py 149 | ``` 150 | 151 | [Find the code here](./first/python.py) 152 | 153 | ## Variables 154 | 155 | Variables are basically storage location that have a name and can store some data which can be changed in future. 156 | 157 | ### Syntax For Variables 158 | 159 | ```sh 160 | VARIABLE_NAME="Value" 161 | ``` 162 | 163 | ### Important 164 | 165 | * Variables are case sensitive 166 | 167 | * By convention, variables are uppercase 168 | 169 | * To use a variable, just write the variable name followed by the `$` sign 170 | 171 | ### Examples Of Variables 172 | 173 | * Example 1 174 | 175 | ```sh 176 | #!/bin/bash 177 | MY_NAME="Madhav Bahl" 178 | echo "Hello, I am $MY_NAME" 179 | ``` 180 | 181 | [Download the code](./variable/name.sh) 182 | 183 | * Example 2 184 | 185 | ```sh 186 | #!/bin/bash 187 | MY_NAME="Madhav Bahl" 188 | echo "Hello, I am ${MY_NAME}" 189 | ``` 190 | 191 | [Download the code](./variable/name2.sh) 192 | 193 | * Example 3: Assign command output to a variable 194 | 195 | ```sh 196 | #!/bin/bash 197 | CONTENTS=$(ls) 198 | echo "The contents of this directory are: " 199 | echo "$CONTENTS" 200 | ``` 201 | 202 | An alternative: 203 | 204 | ```sh 205 | #!/bin/bash 206 | CONTENTS=`ls` 207 | echo "The contents of this directory are: " 208 | echo "$CONTENTS" 209 | ``` 210 | 211 | [Download the code](./variable/comd2.sh) 212 | 213 | * Example 4 214 | 215 | ```sh 216 | #!/bin/bash 217 | SERVER_NAME=$(hostname) 218 | echo "This script is being run on ${SERVER_NAME}" 219 | ``` 220 | 221 | [Download the code](./variable/comd.sh) 222 | 223 | ### Variable Names 224 | 225 | Alphanumeric characters, starting with an alphabet or underscore and can contain digits or underscores in between. 226 | 227 | #### Valid Variable Names 228 | 229 | - THIS3VARIABLE="ABC" 230 | 231 | - THIS_IS_VARIABLE="ABC" 232 | 233 | - thisIsVariable="ABC" 234 | 235 | #### Invalid Variable Names 236 | 237 | - 4Number="NUM" 238 | 239 | - This-Is-Var="VAR" 240 | 241 | No special character apart from underscore is allowed! 242 | 243 | ## Tests 244 | 245 | Scripts are basically needed to remove the need of again and again typing the commands which you use frequently or basically automating tasks. But, what if the script you wrote needs to execute differently under different circumstances? You can make the decisions using tests. 246 | 247 | ### Syntax for tests 248 | 249 | ```sh 250 | [ condition-to-test-for ] 251 | ``` 252 | 253 | #### [Example](./variable/test1.sh) 254 | 255 | ```sh 256 | [ -e /etc/passwd ] 257 | ``` 258 | 259 | This test checks whether /etc/passwd exists, if it does, it returns true (or, it exits with a status of 0). If the file doesnt exists, it returns false (status 1). 260 | 261 | ### File Test Operations 262 | 263 | ```sh 264 | -d FILE_NAM # True if FILE_NAM is a directory 265 | -e FILE_NAM # True if FILE_NAM exists 266 | -f FILE_NAM # True if FILE_NAM exists and is a regular file 267 | -r FILE_NAM # True if FILE_NAM is readable 268 | -s FILE_NAM # True if FILE_NAM exists and is not empty 269 | -w FILE_NAM # True if FILE_NAM has write permission 270 | -x FILE_NAM # True if FILE_NAM is executable 271 | ``` 272 | 273 | ### String Test Operations 274 | 275 | ```sh 276 | -z STRING # True if STRING is empty 277 | -n STRING # True if STRING is not empty 278 | STRING1 = STRIN2 # True if strings are equal 279 | STRING1 != STRIN2 # True if strings are not equal 280 | ``` 281 | 282 | ### Arithmetic Operators 283 | 284 | ```sh 285 | var1 -eq var2 # True if var1 is equal to var2 286 | var1 -ne var2 # True if var1 not equal to var2 287 | var1 -lt var2 # True if var1 is less than var2 288 | var1 -le var2 # True if var1 is less than or equal to var2 289 | var1 -gt var2 # True if var1 is greater than var2 290 | var1 -ge var2 # True if var1 is greater than or equal to var2 291 | ``` 292 | 293 | ## Making Decisions 294 | 295 | Just like any script, shell scripts can make decisions based on conditions. 296 | 297 | ### The IF Statement 298 | 299 | Syntax: 300 | 301 | ```sh 302 | if [ condition-is-true ] 303 | then 304 | command 1 305 | command 2 306 | ... 307 | ... 308 | command N 309 | fi 310 | ``` 311 | 312 | [Example:](./ifElse/ifStat.sh) 313 | 314 | ```sh 315 | #!/bin/bash 316 | SHELL_NAME="bash" 317 | 318 | if [ "$SHELL_NAME" = "bash" ] 319 | then 320 | echo "You are using bash shell" 321 | fi 322 | ``` 323 | 324 | ### IF-ELSE Tree 325 | 326 | Syntax: 327 | 328 | ```sh 329 | if [ condition-is-true ] 330 | then 331 | command 1 332 | command 2 333 | ... 334 | ... 335 | command N 336 | else 337 | command N+1 338 | command N+2 339 | ... 340 | ... 341 | command M 342 | fi 343 | ``` 344 | 345 | [Example:](./ifElse/ifElse.sh) 346 | 347 | ```sh 348 | #!/bin/bash 349 | SHELL_NAME="bash" 350 | 351 | if [ "$SHELL_NAME" = "bash" ] 352 | then 353 | echo "You are using bash shell" 354 | else 355 | echo "You are not using the bash shell" 356 | fi 357 | ``` 358 | 359 | ### IF-ELIF Ladder 360 | 361 | Syntax: 362 | 363 | ```sh 364 | if [ condition-is-true ] 365 | then 366 | command 1 367 | elif [ condition-is-true ] 368 | then 369 | command 2 370 | elif [ condition-is-true ] 371 | then 372 | command 3 373 | else 374 | command 4 375 | fi 376 | ``` 377 | 378 | [Example:](./ifElse/ifElif.sh) 379 | 380 | ```sh 381 | #!/bin/bash 382 | SHELL_NAME="bash" 383 | 384 | if [ "$SHELL_NAME" = "bash" ] 385 | then 386 | echo "You are using bash shell" 387 | elif [ "$SHELL_NAME" = "csh" ] 388 | then 389 | echo "You are using csh shell" 390 | else 391 | echo "You are not using the bash or csh shell" 392 | fi 393 | ``` 394 | 395 | ### Case Statements 396 | 397 | The case statements are an alternative for if statements which are a little easier to read than complex if elif ladder. However, there are some limitations to case statements. 398 | 399 | #### When to use 400 | 401 | If you find yourself using an if statement to compare the same variable against some different/discrete values, you can use a case statements instead of if-elif ladder. 402 | 403 | ```sh 404 | if [ "$VAR"="one" ] 405 | then 406 | ... 407 | elif [ "$VAR"="two" ] 408 | then 409 | ... 410 | elif [ "$VAR"="three" ] 411 | then 412 | ... 413 | ... 414 | ... 415 | else 416 | ... 417 | fi 418 | ``` 419 | 420 | ### Syntax 421 | 422 | ```sh 423 | case "$VAR" in 424 | pattern_1) 425 | # commands when $VAR matches pattern 1 426 | ;; 427 | pattern_2) 428 | # commands when $VAR matches pattern 2 429 | ;; 430 | esac 431 | ``` 432 | 433 | **Note** We can use wildcard to create an else like statement in case. 434 | 435 | ```sh 436 | case "$VAR" in 437 | pattern_1) 438 | # commands when $VAR matches pattern 1 439 | ;; 440 | pattern_2) 441 | # commands when $VAR matches pattern 2 442 | ;; 443 | *) 444 | # This will run if $VAR doesnt match any of the given patterns 445 | ;; 446 | esac 447 | ``` 448 | 449 | #### [Example](./ifElse/case.sh) 450 | 451 | ```sh 452 | #!/bin/bash 453 | read -p "Enter the answer in Y/N: " ANSWER 454 | case "$ANSWER" in 455 | [yY] | [yY][eE][sS]) 456 | echo "The Answer is Yes :)" 457 | ;; 458 | [nN] | [nN][oO]) 459 | echo "The Answer is No :(" 460 | ;; 461 | *) 462 | echo "Invalid Answer :/" 463 | ;; 464 | esac 465 | ``` 466 | 467 | ## Iterative Statements 468 | 469 | Loops can execute a block of code a number of times and are basically used for performing iterations. 470 | 471 | ### The For Loop 472 | 473 | Just like any other programming language, shell scripts also have for loops. 474 | 475 | #### Syntax 476 | 477 | ```sh 478 | for VARIABLE_NAME in ITEM_1 ITEM_N 479 | do 480 | command 1 481 | command 2 482 | ... 483 | ... 484 | command N 485 | done 486 | ``` 487 | 488 | ```sh 489 | for (( VAR=1;VAR 703 | [Example:](./exit-status/error.sh) 704 | 705 | ```sh 706 | #!/bin/bash 707 | ls /randomDirectory # Any Directory which does not exist 708 | echo "$?" # This command will return 2 709 | ``` 710 | 711 | [Another Example:](./exit-status/ping.sh) 712 | 713 | ```sh 714 | #!/bin/bash 715 | HOST="google.com" 716 | ping -c 1 $HOST # -c is used for count, it will send the request, number of times mentioned 717 | RETURN_CODE=$? 718 | if [ "$RETURN_CODE" -eq "0" ] 719 | then 720 | echo "$HOST reachable" 721 | else 722 | echo "$HOST unreachable" 723 | fi 724 | ``` 725 | 726 | ### Logic Operations 727 | Shell scripts supports **logical AND** and **logical OR**. 728 | 729 | ### AND 730 | 731 | The AND Operator results true if all the conditions are satisfied. 732 | 733 | `&& = AND` 734 | 735 | [Example](./exit-status/and.sh) 736 | 737 | ```sh 738 | #!/bin/bash 739 | MY_VAR=10 740 | if [ "$MY_VAR" -ge 5 ] && [ "$MY_VAR" -le 15 ] 741 | then 742 | echo "Given variable is within the range" 743 | fi 744 | ``` 745 | 746 | **Note** While using AND, the second command will run only if the first command returns a 0 exit status. 747 | 748 | Exampe: 749 | 750 | ```bash 751 | mkdir tempDir && cd tempDir && mkdir subTempDir 752 | ``` 753 | 754 | In this example, tempDir is created with `mkdir` command. If it succeeds, then `cd tempDir` is executed. 755 | 756 | ### OR 757 | 758 | The OR Operator results true if any one the conditions are satisfied. 759 | 760 | `|| = OR` 761 | 762 | [Example](./exit-status/or.sh) 763 | 764 | ```sh 765 | #!/bin/bash 766 | MY_VAR=10 767 | if [ "$MY_VAR" -ge 15 ] || [ "$MY_VAR" -le 11 ] 768 | then 769 | echo "Given variable is either greater than 15 or less than 11" 770 | fi 771 | ``` 772 | 773 | **Note** Just like in AND operation, here also, the first condition will be execued first. If it returns the status code 0, then next condition will not be checked. 774 | 775 | ### The Semicolon 776 | 777 | Separate commands on the same line with a semicolon in between to make sure that they all get executed. 778 | The command following the semicolon will always get executed no matter the previous command failed or succeeded. 779 | 780 | Example: 781 | 782 | ```sh 783 | mkdir dir1 ; cd dir1 784 | ``` 785 | 786 | The above code is equivalent to 787 | 788 | ```sh 789 | mkdir dir1 790 | cd dir1 791 | ``` 792 | 793 | ### The Exit Command 794 | 795 | Exit command is used to expicitly define the return code. 796 | If we do not define the exit status of the shell script explicitly, then by default the exit status of the last command executed is taken as the exit status of the script. 797 | We can use exit command anywherer in the script, and as soon as exit command is encountered, the shell script will stop executing. 798 | 799 | ```sh 800 | exit 0 801 | exit 1 802 | exit 2 803 | ... 804 | ... 805 | exit 255 806 | ``` 807 | 808 | [Example:](./exit-status/exitCode.sh) 809 | 810 | ```sh 811 | #!/bin/bash 812 | DIR_NAME="/home/madhav/Desktop/Play" 813 | if [ -e $DIR_NAME ] 814 | then 815 | echo "Given Directory Already Exists" 816 | echo "Moving into ${DIR_NAME}" 817 | cd $DIR_NAME 818 | exit 0 819 | fi 820 | echo "Given Directory Does Not Exists" 821 | mkdir $DIR_NAME 822 | cd $DIR_NAME 823 | exit 1 824 | ``` 825 | 826 | Therefore, using exit code, we can can define custom meanings to exit statuses. 827 | 828 | ## Functions 829 | 830 | A set of instructions which can be reused/called any time from the main program whenever the need for those instructions arrives. Consider a situation that you have a particular module that does a particular job, now let's suppose that job has to be done 20 (say) times in the main program (for example calculating maximum number in an array of numbers). Now, if you write the code for that 20 times, your code would become very large, however, if we write a function for that, and call that function whenever it is required, the code would remain short, easy to read and much more modularised. 831 | 832 | Moreover, it is a great coding practise to keep your code DRY. 833 | DRY stands for Don't Repeat Yourself, i.e., write the code in such a way that you dont have to be copy and pasting same piece of code around everywhere! 834 | 835 | Therefore, functions are great because they make the code DRY, we can write once and use that many times, using functions reduces overall length/size of script. Moreover, functions make program easier to maintain, because they make the code divided into modules making particular place to edit and troubleshoot available in case of bugs/errors. 836 | 837 | Whenever you find yourself repeating a set of instructions, make a function for that. (A function must be defined before use). 838 | 839 | **Note:** It is a good practise to define all your functions at the top before starting the main program or main instructions. 840 | 841 | ### Syntax 842 | 843 | ```sh 844 | function function_name() { 845 | command 1 846 | command 2 847 | command 3 848 | ... 849 | ... 850 | command N 851 | } 852 | ``` 853 | 854 | Or, 855 | 856 | ```sh 857 | function_name() { 858 | command 1 859 | command 2 860 | command 3 861 | ... 862 | ... 863 | command N 864 | } 865 | ``` 866 | 867 | #### [To call a function](./functions/call.sh) 868 | 869 | To call a function, simply write it's name on a line in the script. 870 | 871 | ```sh 872 | #!/bin/bash 873 | function myFunc () { 874 | echo "Shell Scripting Is Fun!" 875 | } 876 | myFunc 877 | ``` 878 | 879 | **Note:** While calling functions, do not use paranthesis like we use in other programming languages. 880 | 881 | ### Calling a function from another function 882 | 883 | To call a function from another function, simply write the function name of the function you want to call. 884 | 885 | [Example:](./functions/greet.sh) 886 | 887 | ```sh 888 | #!/bin/bash 889 | function greetings() { 890 | USER=$(whoami) 891 | echo "Welcome ${USER}" 892 | currentTime 893 | } 894 | function currentTime() { 895 | echo "Current Time Is: $(date +%r)" 896 | } 897 | greetings 898 | ``` 899 | 900 | ### Positional Parameters In Functions 901 | 902 | Just like a shell script, functions can also accept parameters. 903 | 904 | The first parameter is stored in $1 905 | The second parameter is stored in $2 and so on. 906 | $@ contains all the parameters. 907 | 908 | **Note:** $0 is still the name of script itself, not the name of function. 909 | 910 | To provide parameters, just write them after the function name with a white space in between. 911 | 912 | [Example](./functions/greet2.sh) 913 | 914 | ```sh 915 | #!/bin/bash 916 | function greetings() { 917 | for PERSON_NAME in $@ 918 | do 919 | echo "Hello ${PERSON_NAME}" 920 | done 921 | } 922 | greetings World! Random Guy Stranger 923 | ``` 924 | 925 | ### Variable Scope 926 | 927 | ### Global Variables 928 | 929 | All variables have, by default, global scope. Having a global scope means that the value of that variable can be accessed from anywhere in the script. Variables must be defined before it is used. 930 | 931 | **Note:** If a variable is defined within a function, it can not be used until that function is called at least once. 932 | 933 | ### Local Variables 934 | 935 | Local variables can be accessed only from within the function. Local variables are created using `local` keyword and only functions can have local variables. It is a good practise to keep variables inside a function local. 936 | 937 | ```sh 938 | function myFunc () { 939 | local MY_VAR="Hello World" 940 | # MY_VAR is available here 941 | echo "$MY_VAR" 942 | } 943 | # MY_VAR is not available here 944 | ``` 945 | 946 | ### Return codes for function 947 | 948 | A function acts just like a shell script, moreover, a function may be referred to as a shell script within a shell script. Therefore, functions also have an exit status (more precisely, a return code) 949 | 950 | **Implicitly** The exit status of last command executed acts as the return code for the function. 951 | 952 | **Explicitly** Return codes can me custom. `return ` 953 | 954 | **Note** Valid range for return codes = 0 to 255 (0 = Success) 955 | 956 | We can use `$?` to get the return code of a function. 957 | 958 | ```sh 959 | myFunc 960 | echo $? 961 | ``` 962 | 963 | ## Wildcards 964 | 965 | A character or a string patterns that is used to match file and directory names is/are called wildcard(s). 966 | 967 | The process used to expand wildcard pattern into a list of files and/or directories (or basically paths) is called Globbing. 968 | 969 | Wild Cards can be used with most of the commands that require file/dir path as argument. (Example ls,rm,cp etc). 970 | 971 | ### Some Commonly Used Wildcards 972 | 973 | #### * - Matches zero or more characters 974 | 975 | **Example:** 976 | 977 | `*.txt` 978 | `hello.*` 979 | `great*.md` 980 | 981 | #### ? - matches exactly one character 982 | 983 | **Example:** 984 | 985 | `?.md` 986 | `Hello?` 987 | 988 | #### [] - A character class 989 | 990 | This wildcard is used to match any of the characters included between the square brackets (Matching exactly one character). 991 | 992 | **Example:** `He[loym]`, `[AIEOU]` 993 | 994 | #### [!] - matches characters not included within brackets 995 | 996 | It matches exactly one character. 997 | 998 | **Example:** To match a consonant: `[!aeiou]` 999 | 1000 | **Note: We can create range using characer classes** 1001 | 1002 | `[1-5]` -- Mathces number 1 to 5 1003 | 1004 | `[a-e]` -- Matches character a,b,c,d,e 1005 | 1006 | ### Predefined named character classes 1007 | 1008 | * [[:alpha:]] 1009 | 1010 | * [[:alnum:]] 1011 | 1012 | * [[:space:]] 1013 | 1014 | * [[:upper:]]] 1015 | 1016 | * [[:lower:]] 1017 | 1018 | * [[:digit:]] 1019 | 1020 | ### Matching wildcard characters 1021 | 1022 | In case we have to match wildcard characters themselves like `*`, or `?`, we can go with escape character - `\` 1023 | 1024 | Example: `*\?` --> will match all files that end with a question mark. 1025 | 1026 | ### Using wildcards in shell scripts 1027 | 1028 | ```sh 1029 | #!/bin/bash 1030 | # This script will backup all your .txt files in /etc/tmp 1031 | mkdir /etc/tmp 1032 | for FILE in *.txt 1033 | do 1034 | echo "Backing up file $FILE" 1035 | cp $FILE /etc/tmp 1036 | done 1037 | ``` 1038 | 1039 | ## Logging 1040 | 1041 | Logs are used to keep a record of what all happened during the execution of a shell script. 1042 | Logs can store any type of information and can be used to answer the 5 W's: "Who, What, When, Where and Why". 1043 | 1044 | Logs are very useful when your shell script produces a lot of output (that might scroll off your screen). 1045 | 1046 | ### Syslog 1047 | 1048 | The linux OS uses syslog standard for message logging. 1049 | The Syslog standard allows programs to generate messages that can be captured, processed and stored by the system logger. 1050 | 1051 | The syslog standard uses facilities and severities to caegorize messages. Each message is labelled with a facility code and a severiy level, the combinations of whose can be used to determine how the messages will be handled. 1052 | 1053 | #### Facilities 1054 | 1055 | They are used to indicate what type of program or what part of the system the message originated from. 1056 | 1057 | Example: kern (for kernel), user, mail, daemon, auth, local0 to local7 (for custom logs) etc. 1058 | 1059 | #### Severities 1060 | 1061 | As the name suggest, they measure the severity of the message. 1062 | Most severe message are emergency messages and least severe messages are the debug messages. 1063 | 1064 | Example: emerg, alert, crit, err, warning, notice, info, debug 1065 | 1066 | Logs are handled by system logger according to their facilities and severites and are written in a file. There are several logging rules, but they arer configurable and can be changed. 1067 | 1068 | Example: 1069 | 1070 | Some systems have messages stored in `/var/log/messages` or `s/var/log/syslog` 1071 | 1072 | ### The Logger Command 1073 | 1074 | The logger command generates syslog messages. 1075 | `logger "Message"` 1076 | By default, the logger command creates messages with user facility and notice severity. 1077 | 1078 | To specify the facility and severity, use -p option followed by the facility then a `.` then the severity, and then the message. 1079 | 1080 | Example: 1081 | 1082 | ```sh 1083 | logger -p local2.alert "Message" 1084 | ``` 1085 | 1086 | ## Debugging 1087 | 1088 | A bug is an error in a computer program/software that causes it to produce an unexpected or an incorrect result. Most of the bugs are cased by errors in the code and it's design. To fix an error, try to reach to the root of that unexpected behaviour. 1089 | 1090 | The process of finding bugs in the script/program/software and fixing them is called debugging. 1091 | 1092 | The bash shell provides some options that can help you in debugging your script. You can use these options by updating first line of the script. 1093 | 1094 | The most popular of these options is the -x option. 1095 | -x option prints commands and arguments as they execute. It is called print debugging, tracing or an x-trace. 1096 | 1097 | `#!/bin/bash -x` 1098 | 1099 | If you want to do this on the command line/terminal, 1100 | 1101 | `set -x` 1102 | 1103 | set +x to stop debugging. 1104 | 1105 | ![Preview Image](./README-image.png) 1106 | 1107 | set -x will start the x-trace and set +x will stop the x-trace. 1108 | 1109 | Example: 1110 | 1111 | ```sh 1112 | #!/bin/bash-x 1113 | VALUE="Hello World!" 1114 | echo "$VALUE" 1115 | ``` 1116 | 1117 | We can also turn the debugging on for a portion of a script. 1118 | 1119 | ```sh 1120 | #!/bin/bash 1121 | echo "Turning x-trace on!" 1122 | set -x 1123 | VAL="Hello World!" 1124 | echo "$VAL" 1125 | set +x 1126 | VAL="x-trace turned off!" 1127 | echo "Turning x-trace off!" 1128 | echo "$VAL" 1129 | ``` 1130 | 1131 | #### Another useful options 1132 | 1133 | -e = Exit on error 1134 | 1135 | This will cause your script to exit immediately if a command exits with a non-zero exit status. 1136 | It can be combined with other options (like the -x option) like: 1137 | 1138 | ```sh 1139 | #!/bin/bash-xe 1140 | #!/bin/bash-ex 1141 | #!/bin/bash-x-e 1142 | #!/bin/bash-e-x 1143 | ``` 1144 | 1145 | -v = prints shell commands/input lines as they are read. 1146 | It can also be combined with other options just like above. 1147 | 1148 | ## Some Sample Programs 1149 | 1150 | [Click here to see the sample programs](./practise1/) 1151 | 1152 | ## Downloadable PDF 1153 | 1154 | Claim Your Free PDF Here -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | GNU GENERAL PUBLIC LICENSE 2 | Version 3, 29 June 2007 3 | 4 | Copyright (C) 2007 Free Software Foundation, Inc. 5 | Everyone is permitted to copy and distribute verbatim copies 6 | of this license document, but changing it is not allowed. 7 | 8 | Preamble 9 | 10 | The GNU General Public License is a free, copyleft license for 11 | software and other kinds of works. 12 | 13 | The licenses for most software and other practical works are designed 14 | to take away your freedom to share and change the works. By contrast, 15 | the GNU General Public License is intended to guarantee your freedom to 16 | share and change all versions of a program--to make sure it remains free 17 | software for all its users. We, the Free Software Foundation, use the 18 | GNU General Public License for most of our software; it applies also to 19 | any other work released this way by its authors. You can apply it to 20 | your programs, too. 21 | 22 | When we speak of free software, we are referring to freedom, not 23 | price. Our General Public Licenses are designed to make sure that you 24 | have the freedom to distribute copies of free software (and charge for 25 | them if you wish), that you receive source code or can get it if you 26 | want it, that you can change the software or use pieces of it in new 27 | free programs, and that you know you can do these things. 28 | 29 | To protect your rights, we need to prevent others from denying you 30 | these rights or asking you to surrender the rights. Therefore, you have 31 | certain responsibilities if you distribute copies of the software, or if 32 | you modify it: responsibilities to respect the freedom of others. 33 | 34 | For example, if you distribute copies of such a program, whether 35 | gratis or for a fee, you must pass on to the recipients the same 36 | freedoms that you received. You must make sure that they, too, receive 37 | or can get the source code. And you must show them these terms so they 38 | know their rights. 39 | 40 | Developers that use the GNU GPL protect your rights with two steps: 41 | (1) assert copyright on the software, and (2) offer you this License 42 | giving you legal permission to copy, distribute and/or modify it. 43 | 44 | For the developers' and authors' protection, the GPL clearly explains 45 | that there is no warranty for this free software. For both users' and 46 | authors' sake, the GPL requires that modified versions be marked as 47 | changed, so that their problems will not be attributed erroneously to 48 | authors of previous versions. 49 | 50 | Some devices are designed to deny users access to install or run 51 | modified versions of the software inside them, although the manufacturer 52 | can do so. This is fundamentally incompatible with the aim of 53 | protecting users' freedom to change the software. The systematic 54 | pattern of such abuse occurs in the area of products for individuals to 55 | use, which is precisely where it is most unacceptable. Therefore, we 56 | have designed this version of the GPL to prohibit the practice for those 57 | products. If such problems arise substantially in other domains, we 58 | stand ready to extend this provision to those domains in future versions 59 | of the GPL, as needed to protect the freedom of users. 60 | 61 | Finally, every program is threatened constantly by software patents. 62 | States should not allow patents to restrict development and use of 63 | software on general-purpose computers, but in those that do, we wish to 64 | avoid the special danger that patents applied to a free program could 65 | make it effectively proprietary. To prevent this, the GPL assures that 66 | patents cannot be used to render the program non-free. 67 | 68 | The precise terms and conditions for copying, distribution and 69 | modification follow. 70 | 71 | TERMS AND CONDITIONS 72 | 73 | 0. Definitions. 74 | 75 | "This License" refers to version 3 of the GNU General Public License. 76 | 77 | "Copyright" also means copyright-like laws that apply to other kinds of 78 | works, such as semiconductor masks. 79 | 80 | "The Program" refers to any copyrightable work licensed under this 81 | License. Each licensee is addressed as "you". "Licensees" and 82 | "recipients" may be individuals or organizations. 83 | 84 | To "modify" a work means to copy from or adapt all or part of the work 85 | in a fashion requiring copyright permission, other than the making of an 86 | exact copy. The resulting work is called a "modified version" of the 87 | earlier work or a work "based on" the earlier work. 88 | 89 | A "covered work" means either the unmodified Program or a work based 90 | on the Program. 91 | 92 | To "propagate" a work means to do anything with it that, without 93 | permission, would make you directly or secondarily liable for 94 | infringement under applicable copyright law, except executing it on a 95 | computer or modifying a private copy. Propagation includes copying, 96 | distribution (with or without modification), making available to the 97 | public, and in some countries other activities as well. 98 | 99 | To "convey" a work means any kind of propagation that enables other 100 | parties to make or receive copies. Mere interaction with a user through 101 | a computer network, with no transfer of a copy, is not conveying. 102 | 103 | An interactive user interface displays "Appropriate Legal Notices" 104 | to the extent that it includes a convenient and prominently visible 105 | feature that (1) displays an appropriate copyright notice, and (2) 106 | tells the user that there is no warranty for the work (except to the 107 | extent that warranties are provided), that licensees may convey the 108 | work under this License, and how to view a copy of this License. If 109 | the interface presents a list of user commands or options, such as a 110 | menu, a prominent item in the list meets this criterion. 111 | 112 | 1. Source Code. 113 | 114 | The "source code" for a work means the preferred form of the work 115 | for making modifications to it. "Object code" means any non-source 116 | form of a work. 117 | 118 | A "Standard Interface" means an interface that either is an official 119 | standard defined by a recognized standards body, or, in the case of 120 | interfaces specified for a particular programming language, one that 121 | is widely used among developers working in that language. 122 | 123 | The "System Libraries" of an executable work include anything, other 124 | than the work as a whole, that (a) is included in the normal form of 125 | packaging a Major Component, but which is not part of that Major 126 | Component, and (b) serves only to enable use of the work with that 127 | Major Component, or to implement a Standard Interface for which an 128 | implementation is available to the public in source code form. A 129 | "Major Component", in this context, means a major essential component 130 | (kernel, window system, and so on) of the specific operating system 131 | (if any) on which the executable work runs, or a compiler used to 132 | produce the work, or an object code interpreter used to run it. 133 | 134 | The "Corresponding Source" for a work in object code form means all 135 | the source code needed to generate, install, and (for an executable 136 | work) run the object code and to modify the work, including scripts to 137 | control those activities. However, it does not include the work's 138 | System Libraries, or general-purpose tools or generally available free 139 | programs which are used unmodified in performing those activities but 140 | which are not part of the work. For example, Corresponding Source 141 | includes interface definition files associated with source files for 142 | the work, and the source code for shared libraries and dynamically 143 | linked subprograms that the work is specifically designed to require, 144 | such as by intimate data communication or control flow between those 145 | subprograms and other parts of the work. 146 | 147 | The Corresponding Source need not include anything that users 148 | can regenerate automatically from other parts of the Corresponding 149 | Source. 150 | 151 | The Corresponding Source for a work in source code form is that 152 | same work. 153 | 154 | 2. Basic Permissions. 155 | 156 | All rights granted under this License are granted for the term of 157 | copyright on the Program, and are irrevocable provided the stated 158 | conditions are met. This License explicitly affirms your unlimited 159 | permission to run the unmodified Program. The output from running a 160 | covered work is covered by this License only if the output, given its 161 | content, constitutes a covered work. This License acknowledges your 162 | rights of fair use or other equivalent, as provided by copyright law. 163 | 164 | You may make, run and propagate covered works that you do not 165 | convey, without conditions so long as your license otherwise remains 166 | in force. You may convey covered works to others for the sole purpose 167 | of having them make modifications exclusively for you, or provide you 168 | with facilities for running those works, provided that you comply with 169 | the terms of this License in conveying all material for which you do 170 | not control copyright. Those thus making or running the covered works 171 | for you must do so exclusively on your behalf, under your direction 172 | and control, on terms that prohibit them from making any copies of 173 | your copyrighted material outside their relationship with you. 174 | 175 | Conveying under any other circumstances is permitted solely under 176 | the conditions stated below. Sublicensing is not allowed; section 10 177 | makes it unnecessary. 178 | 179 | 3. Protecting Users' Legal Rights From Anti-Circumvention Law. 180 | 181 | No covered work shall be deemed part of an effective technological 182 | measure under any applicable law fulfilling obligations under article 183 | 11 of the WIPO copyright treaty adopted on 20 December 1996, or 184 | similar laws prohibiting or restricting circumvention of such 185 | measures. 186 | 187 | When you convey a covered work, you waive any legal power to forbid 188 | circumvention of technological measures to the extent such circumvention 189 | is effected by exercising rights under this License with respect to 190 | the covered work, and you disclaim any intention to limit operation or 191 | modification of the work as a means of enforcing, against the work's 192 | users, your or third parties' legal rights to forbid circumvention of 193 | technological measures. 194 | 195 | 4. Conveying Verbatim Copies. 196 | 197 | You may convey verbatim copies of the Program's source code as you 198 | receive it, in any medium, provided that you conspicuously and 199 | appropriately publish on each copy an appropriate copyright notice; 200 | keep intact all notices stating that this License and any 201 | non-permissive terms added in accord with section 7 apply to the code; 202 | keep intact all notices of the absence of any warranty; and give all 203 | recipients a copy of this License along with the Program. 204 | 205 | You may charge any price or no price for each copy that you convey, 206 | and you may offer support or warranty protection for a fee. 207 | 208 | 5. Conveying Modified Source Versions. 209 | 210 | You may convey a work based on the Program, or the modifications to 211 | produce it from the Program, in the form of source code under the 212 | terms of section 4, provided that you also meet all of these conditions: 213 | 214 | a) The work must carry prominent notices stating that you modified 215 | it, and giving a relevant date. 216 | 217 | b) The work must carry prominent notices stating that it is 218 | released under this License and any conditions added under section 219 | 7. This requirement modifies the requirement in section 4 to 220 | "keep intact all notices". 221 | 222 | c) You must license the entire work, as a whole, under this 223 | License to anyone who comes into possession of a copy. This 224 | License will therefore apply, along with any applicable section 7 225 | additional terms, to the whole of the work, and all its parts, 226 | regardless of how they are packaged. This License gives no 227 | permission to license the work in any other way, but it does not 228 | invalidate such permission if you have separately received it. 229 | 230 | d) If the work has interactive user interfaces, each must display 231 | Appropriate Legal Notices; however, if the Program has interactive 232 | interfaces that do not display Appropriate Legal Notices, your 233 | work need not make them do so. 234 | 235 | A compilation of a covered work with other separate and independent 236 | works, which are not by their nature extensions of the covered work, 237 | and which are not combined with it such as to form a larger program, 238 | in or on a volume of a storage or distribution medium, is called an 239 | "aggregate" if the compilation and its resulting copyright are not 240 | used to limit the access or legal rights of the compilation's users 241 | beyond what the individual works permit. Inclusion of a covered work 242 | in an aggregate does not cause this License to apply to the other 243 | parts of the aggregate. 244 | 245 | 6. Conveying Non-Source Forms. 246 | 247 | You may convey a covered work in object code form under the terms 248 | of sections 4 and 5, provided that you also convey the 249 | machine-readable Corresponding Source under the terms of this License, 250 | in one of these ways: 251 | 252 | a) Convey the object code in, or embodied in, a physical product 253 | (including a physical distribution medium), accompanied by the 254 | Corresponding Source fixed on a durable physical medium 255 | customarily used for software interchange. 256 | 257 | b) Convey the object code in, or embodied in, a physical product 258 | (including a physical distribution medium), accompanied by a 259 | written offer, valid for at least three years and valid for as 260 | long as you offer spare parts or customer support for that product 261 | model, to give anyone who possesses the object code either (1) a 262 | copy of the Corresponding Source for all the software in the 263 | product that is covered by this License, on a durable physical 264 | medium customarily used for software interchange, for a price no 265 | more than your reasonable cost of physically performing this 266 | conveying of source, or (2) access to copy the 267 | Corresponding Source from a network server at no charge. 268 | 269 | c) Convey individual copies of the object code with a copy of the 270 | written offer to provide the Corresponding Source. This 271 | alternative is allowed only occasionally and noncommercially, and 272 | only if you received the object code with such an offer, in accord 273 | with subsection 6b. 274 | 275 | d) Convey the object code by offering access from a designated 276 | place (gratis or for a charge), and offer equivalent access to the 277 | Corresponding Source in the same way through the same place at no 278 | further charge. You need not require recipients to copy the 279 | Corresponding Source along with the object code. If the place to 280 | copy the object code is a network server, the Corresponding Source 281 | may be on a different server (operated by you or a third party) 282 | that supports equivalent copying facilities, provided you maintain 283 | clear directions next to the object code saying where to find the 284 | Corresponding Source. Regardless of what server hosts the 285 | Corresponding Source, you remain obligated to ensure that it is 286 | available for as long as needed to satisfy these requirements. 287 | 288 | e) Convey the object code using peer-to-peer transmission, provided 289 | you inform other peers where the object code and Corresponding 290 | Source of the work are being offered to the general public at no 291 | charge under subsection 6d. 292 | 293 | A separable portion of the object code, whose source code is excluded 294 | from the Corresponding Source as a System Library, need not be 295 | included in conveying the object code work. 296 | 297 | A "User Product" is either (1) a "consumer product", which means any 298 | tangible personal property which is normally used for personal, family, 299 | or household purposes, or (2) anything designed or sold for incorporation 300 | into a dwelling. In determining whether a product is a consumer product, 301 | doubtful cases shall be resolved in favor of coverage. For a particular 302 | product received by a particular user, "normally used" refers to a 303 | typical or common use of that class of product, regardless of the status 304 | of the particular user or of the way in which the particular user 305 | actually uses, or expects or is expected to use, the product. A product 306 | is a consumer product regardless of whether the product has substantial 307 | commercial, industrial or non-consumer uses, unless such uses represent 308 | the only significant mode of use of the product. 309 | 310 | "Installation Information" for a User Product means any methods, 311 | procedures, authorization keys, or other information required to install 312 | and execute modified versions of a covered work in that User Product from 313 | a modified version of its Corresponding Source. The information must 314 | suffice to ensure that the continued functioning of the modified object 315 | code is in no case prevented or interfered with solely because 316 | modification has been made. 317 | 318 | If you convey an object code work under this section in, or with, or 319 | specifically for use in, a User Product, and the conveying occurs as 320 | part of a transaction in which the right of possession and use of the 321 | User Product is transferred to the recipient in perpetuity or for a 322 | fixed term (regardless of how the transaction is characterized), the 323 | Corresponding Source conveyed under this section must be accompanied 324 | by the Installation Information. But this requirement does not apply 325 | if neither you nor any third party retains the ability to install 326 | modified object code on the User Product (for example, the work has 327 | been installed in ROM). 328 | 329 | The requirement to provide Installation Information does not include a 330 | requirement to continue to provide support service, warranty, or updates 331 | for a work that has been modified or installed by the recipient, or for 332 | the User Product in which it has been modified or installed. Access to a 333 | network may be denied when the modification itself materially and 334 | adversely affects the operation of the network or violates the rules and 335 | protocols for communication across the network. 336 | 337 | Corresponding Source conveyed, and Installation Information provided, 338 | in accord with this section must be in a format that is publicly 339 | documented (and with an implementation available to the public in 340 | source code form), and must require no special password or key for 341 | unpacking, reading or copying. 342 | 343 | 7. Additional Terms. 344 | 345 | "Additional permissions" are terms that supplement the terms of this 346 | License by making exceptions from one or more of its conditions. 347 | Additional permissions that are applicable to the entire Program shall 348 | be treated as though they were included in this License, to the extent 349 | that they are valid under applicable law. If additional permissions 350 | apply only to part of the Program, that part may be used separately 351 | under those permissions, but the entire Program remains governed by 352 | this License without regard to the additional permissions. 353 | 354 | When you convey a copy of a covered work, you may at your option 355 | remove any additional permissions from that copy, or from any part of 356 | it. (Additional permissions may be written to require their own 357 | removal in certain cases when you modify the work.) You may place 358 | additional permissions on material, added by you to a covered work, 359 | for which you have or can give appropriate copyright permission. 360 | 361 | Notwithstanding any other provision of this License, for material you 362 | add to a covered work, you may (if authorized by the copyright holders of 363 | that material) supplement the terms of this License with terms: 364 | 365 | a) Disclaiming warranty or limiting liability differently from the 366 | terms of sections 15 and 16 of this License; or 367 | 368 | b) Requiring preservation of specified reasonable legal notices or 369 | author attributions in that material or in the Appropriate Legal 370 | Notices displayed by works containing it; or 371 | 372 | c) Prohibiting misrepresentation of the origin of that material, or 373 | requiring that modified versions of such material be marked in 374 | reasonable ways as different from the original version; or 375 | 376 | d) Limiting the use for publicity purposes of names of licensors or 377 | authors of the material; or 378 | 379 | e) Declining to grant rights under trademark law for use of some 380 | trade names, trademarks, or service marks; or 381 | 382 | f) Requiring indemnification of licensors and authors of that 383 | material by anyone who conveys the material (or modified versions of 384 | it) with contractual assumptions of liability to the recipient, for 385 | any liability that these contractual assumptions directly impose on 386 | those licensors and authors. 387 | 388 | All other non-permissive additional terms are considered "further 389 | restrictions" within the meaning of section 10. If the Program as you 390 | received it, or any part of it, contains a notice stating that it is 391 | governed by this License along with a term that is a further 392 | restriction, you may remove that term. If a license document contains 393 | a further restriction but permits relicensing or conveying under this 394 | License, you may add to a covered work material governed by the terms 395 | of that license document, provided that the further restriction does 396 | not survive such relicensing or conveying. 397 | 398 | If you add terms to a covered work in accord with this section, you 399 | must place, in the relevant source files, a statement of the 400 | additional terms that apply to those files, or a notice indicating 401 | where to find the applicable terms. 402 | 403 | Additional terms, permissive or non-permissive, may be stated in the 404 | form of a separately written license, or stated as exceptions; 405 | the above requirements apply either way. 406 | 407 | 8. Termination. 408 | 409 | You may not propagate or modify a covered work except as expressly 410 | provided under this License. Any attempt otherwise to propagate or 411 | modify it is void, and will automatically terminate your rights under 412 | this License (including any patent licenses granted under the third 413 | paragraph of section 11). 414 | 415 | However, if you cease all violation of this License, then your 416 | license from a particular copyright holder is reinstated (a) 417 | provisionally, unless and until the copyright holder explicitly and 418 | finally terminates your license, and (b) permanently, if the copyright 419 | holder fails to notify you of the violation by some reasonable means 420 | prior to 60 days after the cessation. 421 | 422 | Moreover, your license from a particular copyright holder is 423 | reinstated permanently if the copyright holder notifies you of the 424 | violation by some reasonable means, this is the first time you have 425 | received notice of violation of this License (for any work) from that 426 | copyright holder, and you cure the violation prior to 30 days after 427 | your receipt of the notice. 428 | 429 | Termination of your rights under this section does not terminate the 430 | licenses of parties who have received copies or rights from you under 431 | this License. If your rights have been terminated and not permanently 432 | reinstated, you do not qualify to receive new licenses for the same 433 | material under section 10. 434 | 435 | 9. Acceptance Not Required for Having Copies. 436 | 437 | You are not required to accept this License in order to receive or 438 | run a copy of the Program. Ancillary propagation of a covered work 439 | occurring solely as a consequence of using peer-to-peer transmission 440 | to receive a copy likewise does not require acceptance. However, 441 | nothing other than this License grants you permission to propagate or 442 | modify any covered work. These actions infringe copyright if you do 443 | not accept this License. Therefore, by modifying or propagating a 444 | covered work, you indicate your acceptance of this License to do so. 445 | 446 | 10. Automatic Licensing of Downstream Recipients. 447 | 448 | Each time you convey a covered work, the recipient automatically 449 | receives a license from the original licensors, to run, modify and 450 | propagate that work, subject to this License. You are not responsible 451 | for enforcing compliance by third parties with this License. 452 | 453 | An "entity transaction" is a transaction transferring control of an 454 | organization, or substantially all assets of one, or subdividing an 455 | organization, or merging organizations. If propagation of a covered 456 | work results from an entity transaction, each party to that 457 | transaction who receives a copy of the work also receives whatever 458 | licenses to the work the party's predecessor in interest had or could 459 | give under the previous paragraph, plus a right to possession of the 460 | Corresponding Source of the work from the predecessor in interest, if 461 | the predecessor has it or can get it with reasonable efforts. 462 | 463 | You may not impose any further restrictions on the exercise of the 464 | rights granted or affirmed under this License. For example, you may 465 | not impose a license fee, royalty, or other charge for exercise of 466 | rights granted under this License, and you may not initiate litigation 467 | (including a cross-claim or counterclaim in a lawsuit) alleging that 468 | any patent claim is infringed by making, using, selling, offering for 469 | sale, or importing the Program or any portion of it. 470 | 471 | 11. Patents. 472 | 473 | A "contributor" is a copyright holder who authorizes use under this 474 | License of the Program or a work on which the Program is based. The 475 | work thus licensed is called the contributor's "contributor version". 476 | 477 | A contributor's "essential patent claims" are all patent claims 478 | owned or controlled by the contributor, whether already acquired or 479 | hereafter acquired, that would be infringed by some manner, permitted 480 | by this License, of making, using, or selling its contributor version, 481 | but do not include claims that would be infringed only as a 482 | consequence of further modification of the contributor version. For 483 | purposes of this definition, "control" includes the right to grant 484 | patent sublicenses in a manner consistent with the requirements of 485 | this License. 486 | 487 | Each contributor grants you a non-exclusive, worldwide, royalty-free 488 | patent license under the contributor's essential patent claims, to 489 | make, use, sell, offer for sale, import and otherwise run, modify and 490 | propagate the contents of its contributor version. 491 | 492 | In the following three paragraphs, a "patent license" is any express 493 | agreement or commitment, however denominated, not to enforce a patent 494 | (such as an express permission to practice a patent or covenant not to 495 | sue for patent infringement). To "grant" such a patent license to a 496 | party means to make such an agreement or commitment not to enforce a 497 | patent against the party. 498 | 499 | If you convey a covered work, knowingly relying on a patent license, 500 | and the Corresponding Source of the work is not available for anyone 501 | to copy, free of charge and under the terms of this License, through a 502 | publicly available network server or other readily accessible means, 503 | then you must either (1) cause the Corresponding Source to be so 504 | available, or (2) arrange to deprive yourself of the benefit of the 505 | patent license for this particular work, or (3) arrange, in a manner 506 | consistent with the requirements of this License, to extend the patent 507 | license to downstream recipients. "Knowingly relying" means you have 508 | actual knowledge that, but for the patent license, your conveying the 509 | covered work in a country, or your recipient's use of the covered work 510 | in a country, would infringe one or more identifiable patents in that 511 | country that you have reason to believe are valid. 512 | 513 | If, pursuant to or in connection with a single transaction or 514 | arrangement, you convey, or propagate by procuring conveyance of, a 515 | covered work, and grant a patent license to some of the parties 516 | receiving the covered work authorizing them to use, propagate, modify 517 | or convey a specific copy of the covered work, then the patent license 518 | you grant is automatically extended to all recipients of the covered 519 | work and works based on it. 520 | 521 | A patent license is "discriminatory" if it does not include within 522 | the scope of its coverage, prohibits the exercise of, or is 523 | conditioned on the non-exercise of one or more of the rights that are 524 | specifically granted under this License. You may not convey a covered 525 | work if you are a party to an arrangement with a third party that is 526 | in the business of distributing software, under which you make payment 527 | to the third party based on the extent of your activity of conveying 528 | the work, and under which the third party grants, to any of the 529 | parties who would receive the covered work from you, a discriminatory 530 | patent license (a) in connection with copies of the covered work 531 | conveyed by you (or copies made from those copies), or (b) primarily 532 | for and in connection with specific products or compilations that 533 | contain the covered work, unless you entered into that arrangement, 534 | or that patent license was granted, prior to 28 March 2007. 535 | 536 | Nothing in this License shall be construed as excluding or limiting 537 | any implied license or other defenses to infringement that may 538 | otherwise be available to you under applicable patent law. 539 | 540 | 12. No Surrender of Others' Freedom. 541 | 542 | If conditions are imposed on you (whether by court order, agreement or 543 | otherwise) that contradict the conditions of this License, they do not 544 | excuse you from the conditions of this License. If you cannot convey a 545 | covered work so as to satisfy simultaneously your obligations under this 546 | License and any other pertinent obligations, then as a consequence you may 547 | not convey it at all. For example, if you agree to terms that obligate you 548 | to collect a royalty for further conveying from those to whom you convey 549 | the Program, the only way you could satisfy both those terms and this 550 | License would be to refrain entirely from conveying the Program. 551 | 552 | 13. Use with the GNU Affero General Public License. 553 | 554 | Notwithstanding any other provision of this License, you have 555 | permission to link or combine any covered work with a work licensed 556 | under version 3 of the GNU Affero General Public License into a single 557 | combined work, and to convey the resulting work. The terms of this 558 | License will continue to apply to the part which is the covered work, 559 | but the special requirements of the GNU Affero General Public License, 560 | section 13, concerning interaction through a network will apply to the 561 | combination as such. 562 | 563 | 14. Revised Versions of this License. 564 | 565 | The Free Software Foundation may publish revised and/or new versions of 566 | the GNU General Public License from time to time. Such new versions will 567 | be similar in spirit to the present version, but may differ in detail to 568 | address new problems or concerns. 569 | 570 | Each version is given a distinguishing version number. If the 571 | Program specifies that a certain numbered version of the GNU General 572 | Public License "or any later version" applies to it, you have the 573 | option of following the terms and conditions either of that numbered 574 | version or of any later version published by the Free Software 575 | Foundation. If the Program does not specify a version number of the 576 | GNU General Public License, you may choose any version ever published 577 | by the Free Software Foundation. 578 | 579 | If the Program specifies that a proxy can decide which future 580 | versions of the GNU General Public License can be used, that proxy's 581 | public statement of acceptance of a version permanently authorizes you 582 | to choose that version for the Program. 583 | 584 | Later license versions may give you additional or different 585 | permissions. However, no additional obligations are imposed on any 586 | author or copyright holder as a result of your choosing to follow a 587 | later version. 588 | 589 | 15. Disclaimer of Warranty. 590 | 591 | THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY 592 | APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT 593 | HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY 594 | OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, 595 | THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 596 | PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM 597 | IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF 598 | ALL NECESSARY SERVICING, REPAIR OR CORRECTION. 599 | 600 | 16. Limitation of Liability. 601 | 602 | IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING 603 | WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS 604 | THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY 605 | GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE 606 | USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF 607 | DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD 608 | PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), 609 | EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF 610 | SUCH DAMAGES. 611 | 612 | 17. Interpretation of Sections 15 and 16. 613 | 614 | If the disclaimer of warranty and limitation of liability provided 615 | above cannot be given local legal effect according to their terms, 616 | reviewing courts shall apply local law that most closely approximates 617 | an absolute waiver of all civil liability in connection with the 618 | Program, unless a warranty or assumption of liability accompanies a 619 | copy of the Program in return for a fee. 620 | 621 | END OF TERMS AND CONDITIONS 622 | 623 | How to Apply These Terms to Your New Programs 624 | 625 | If you develop a new program, and you want it to be of the greatest 626 | possible use to the public, the best way to achieve this is to make it 627 | free software which everyone can redistribute and change under these terms. 628 | 629 | To do so, attach the following notices to the program. It is safest 630 | to attach them to the start of each source file to most effectively 631 | state the exclusion of warranty; and each file should have at least 632 | the "copyright" line and a pointer to where the full notice is found. 633 | 634 | 635 | Copyright (C) 636 | 637 | This program is free software: you can redistribute it and/or modify 638 | it under the terms of the GNU General Public License as published by 639 | the Free Software Foundation, either version 3 of the License, or 640 | (at your option) any later version. 641 | 642 | This program is distributed in the hope that it will be useful, 643 | but WITHOUT ANY WARRANTY; without even the implied warranty of 644 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 645 | GNU General Public License for more details. 646 | 647 | You should have received a copy of the GNU General Public License 648 | along with this program. If not, see . 649 | 650 | Also add information on how to contact you by electronic and paper mail. 651 | 652 | If the program does terminal interaction, make it output a short 653 | notice like this when it starts in an interactive mode: 654 | 655 | Copyright (C) 656 | This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'. 657 | This is free software, and you are welcome to redistribute it 658 | under certain conditions; type `show c' for details. 659 | 660 | The hypothetical commands `show w' and `show c' should show the appropriate 661 | parts of the General Public License. Of course, your program's commands 662 | might be different; for a GUI interface, you would use an "about box". 663 | 664 | You should also get your employer (if you work as a programmer) or school, 665 | if any, to sign a "copyright disclaimer" for the program, if necessary. 666 | For more information on this, and how to apply and follow the GNU GPL, see 667 | . 668 | 669 | The GNU General Public License does not permit incorporating your program 670 | into proprietary programs. If your program is a subroutine library, you 671 | may consider it more useful to permit linking proprietary applications with 672 | the library. If this is what you want to do, use the GNU Lesser General 673 | Public License instead of this License. But first, please read 674 | . 675 | --------------------------------------------------------------------------------