Bash Scripting Workshop
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This document provides an overview of Bash scripting concepts including file systems, variables and strings, math operations, file ownership and permissions, users and privileges, processes and subshells, loops, conditional statements, I/O redirection, named pipes, signals, and GUI tools. It also includes examples of Bluetooth file sharing, auto-shutdown scripts, lockscreen notifications, web crawling scripts, and time tracking automation. References are provided for further reading.
![Math
● echo $((1+1))
● echo $[1+1]
● echo `expr 1 + 1`
● A=$((B*C))
● let A+=1
● echo "3.4+7/8-(5.94*3.14)" | bc](https://image.slidesharecdn.com/bashworkshop-120105023711-phpapp01/85/Bash-Scripting-Workshop-4-320.jpg)
![if and switch case
● If then, else, elif, fi
if [ -d $F ]; then
rm -rdf $F
elif [ -f $F ]; then
rm $F
else
echo “Unknown file type”
fi
● case, esac
while read l; do
case $l in
1) echo "One";;
2) echo "Two";;
3) echo "Three";;
*) echo "Invalid"; break;;
esac
done](https://image.slidesharecdn.com/bashworkshop-120105023711-phpapp01/85/Bash-Scripting-Workshop-9-320.jpg)
![Example Codes
● Bluetooth Obex-push
NEW_FILE_NAME=`echo $1 | awk -vFS="/" '{print $NF;}'`
ussp-push 00:22:65:89:22:E6@9 "$1" "$NEW_FILE_NAME"
● Close the computer when your browser finishes downloading
your_file
while true; do sleep 5; if [ -z "`fuser ~/your_file`" ]; then break;
fi; done; sudo init 0
● Tell me the time whenever I lock my screen or unlock it
● Simple spider using curl and wget
● Log your time easily and report to a Redmine service
● Think of more ...](https://image.slidesharecdn.com/bashworkshop-120105023711-phpapp01/85/Bash-Scripting-Workshop-14-320.jpg)
Bash Scripting Workshop
- 1. Bash Scripting Prepared by Ahmed Magdy Ezzeldin
- 2. File System ● / is not allowed in a file name ● file extensions are not important ● File and folder names are case sensitive ● Names containing spaces are escaped by or "" ● Hidden files start with . ● Current directory alias . and parent directory alias .. ● ls, ls -a, ls -l, cp, mv, rm, rm -rdf, ln, ln -sf
- 3. Variable and Strings ● Strings are enclosed in “” '' or just written with spaces escaped by VAR=”How are you” VAR='How are you' VAR=HOW are you ● Variables $VAR ${VAR} # e.g. ${FILE}.txt echo “my name is $NAME” echo “my name is “$NAME read VAR read VAR1 VAR2
- 4. Math ● echo $((1+1)) ● echo $[1+1] ● echo `expr 1 + 1` ● A=$((B*C)) ● let A+=1 ● echo "3.4+7/8-(5.94*3.14)" | bc
- 5. File Ownership and Permissions ● Group and Ownership chown, chgrp, ls -l chown user:group file sudo chown ● Permissions of files and directories chmod 755 file chmod +x file chmod -x file (r)ead (w)rite e(x)ecute 4 2 1
- 6. Users, su, sudo ● su, sudo, visudo, /etc/sudoers, su user ● sudo bash ● /etc/passwd ● ~/
- 7. Processes and Subshells ● ps, pgrep, top, jobs, fg, &, kill, signals ● Sub-shells from : ● Loops ● $() ● Back ticks `` ● bash command ● /proc ● fuser
- 8. Loops ● While loop while read VAR; do echo $VAR; done ● For each loop for VAR in {1..5}; do echo $VAR; done for VAR in 1 2 3 4 5; do echo $VAR; done for VAR in {0..10..2}; do echo $VAR; done for VAR in $(seq 0 2 10); do echo $VAR; done ● For loop with counter for (( i=0; i<=10; i+=2 )); do echo $i; done
- 9. if and switch case ● If then, else, elif, fi if [ -d $F ]; then rm -rdf $F elif [ -f $F ]; then rm $F else echo “Unknown file type” fi ● case, esac while read l; do case $l in 1) echo "One";; 2) echo "Two";; 3) echo "Three";; *) echo "Invalid"; break;; esac done
- 10. I/O Redirection ● >, >>, <, &>, 2&>, 2>, | echo “error” 1>&2 # redirect std_output to std_err some_error_producing_command 2>&1 some_command &>> log_file_errors_and_output some_command >> log_file_output_only some_command 2>> log_file_errors_only command | filter_command command < file command > file # truncates and writes into file command1 2>&1 | command2 command1 |& command2 ● Mute by redirecting to /dev/null file
- 11. Named Pipes and Network and Signal Processing ● Network exec 9<>/dev/tcp/google.com/80 echo -e "GET / HTTP/1.0nn" >&9 while read line <&9; do echo $line; done ● Named Pipes mkfifo pipe while read l; do echo $l; done < pipe echo “hi” > pipe # on another terminal window ● Signal Processing #!/bin/bash function handle_signal () { echo "Hi man I got the signal" } trap "handle_signal; exit" SIGINT sleep 100
- 12. Cool Stuff and GUI ● Install these: libnotify-bin, zenity, festival ● date '+%l oclock' | festival –tts ● zenity --list --hide-header --text="Are you coming today?" --checklist --column "" --column "" FALSE "Yes" FALSE "No" FALSE "May be" ● zenity --calendar --date-format="%Y/%m/%d" ● zenity --text="Select Hour" --title="Select Hour" --scale --min-value=0 --max- value=24 --value=17 ● zenity --text="Select Minutes" --title="Select Minutes" --scale --min-value=0 --max-value=59 --value=0 ● zenity --info --text="Did you know this info" ● zenity --error --text="There is an error" ● zenity --entry | festival --tts ● zenity --file-selection ● <progres command> | zenity --progress --auto-close ● notify-send -t 10 "hi man" "details"
- 13. Launchers ● When you drag a file or folder onto a launcher it is sent as $1 to the launcher script
- 14. Example Codes ● Bluetooth Obex-push NEW_FILE_NAME=`echo $1 | awk -vFS="/" '{print $NF;}'` ussp-push 00:22:65:89:22:E6@9 "$1" "$NEW_FILE_NAME" ● Close the computer when your browser finishes downloading your_file while true; do sleep 5; if [ -z "`fuser ~/your_file`" ]; then break; fi; done; sudo init 0 ● Tell me the time whenever I lock my screen or unlock it ● Simple spider using curl and wget ● Log your time easily and report to a Redmine service ● Think of more ...
- 15. Thank you
- 16. References http://www.linuxcommand.org/lts0040.php http://www.cyberciti.biz/faq/bash-for-loop/ http://linuxcommand.org/wss0160.php http://tldp.org/HOWTO/Bash-Prog-Intro-HOWTO-10.html http://wiki.bash-hackers.org/syntax/redirection http://www.kernel.org/doc/man-pages/online/pages/man5/proc.5.html