Advanced Bash Loops Tutorial

The BASH scripting language provides a very handy 'loop' features.  we have discussed that we can chain certain commands such as:

strace -p `pgrep -u root sshd`

This command however, provided that pgrep returns more than 1 process, will result in an error, since strace does not expect more than 1 process at a time. To overcome this issue, we can edit the line and add a loop control structure:

for i in `pgrep -u root sshd`; do strace -p $i ; done

What the above line will do is to create a for loop and for each result of pgrep to run strace -p.