[Quick Tips: Bash Script]: A Tutorial on Bash Script

A Tutorial on Bash Script

Use bash For Loop In One Line

Run Command 5 Times

for i in {1..5}; do COMMAND-HERE; done

OR

for((i=1;i<=10;i+=2)); do echo "Welcome $i times"; done

Work On Files

for i in *; do echo $i; done

OR

for i in /etc/*.conf; do cp $i /backup; done

For Loop To Remove Files

Use a Bash For Loop To Delete Files in Unix

for f in /path/to/dir/*.txt do # if file, delete it [ -f "$f" ] && rm "$f" done

See Bash for loop tutorial for more information.

Use a KSH For Loop To Delete Files in Unix

for f in /path/to/dir/*.c~; do # if it is a file, delete it if [ -f $f ] then rm "$f" fi done For While Loop Through File Contents Script while COMMANDS do COMMANDS done OR while read line do echo "$line" done < /path/to/input.txt In this example, read /etc/passwd file line by line using while loop: #!/bin/bash while IFS= read -r line do echo "$line" done < "/etc/passwd" Another example: #!/bin/bash ## script.sh ## _file="${1:-/dev/null}" #fail safe while IFS= read -r line do # Do something on $line echo "$line" done < "$_file" Run it as follows: chmod +x script.sh ./script.sh /path/to/text/file.name