The while-loop

while <LIST1> ; do
  <LIST2>
done

The while-loop is relatively simple in what it does: it executes the command list <LIST1> and if the exit code of it was 0 (TRUE) it executes <LIST2>. This happens again and again until <LIST1> returns FALSE.

This is exactly the opposite of the until loop.

Like all loops (both for-loops, while and until), this loop can be

• terminated (broken) by the break command, optionally as break N to break N levels of nested loops
• forced to immediately do the next iteration using the continue command, optionally as continue N analog to break N

The return status is the one of the last command executed in <LIST2>, or 0 (TRUE) if none was executed.

• Internal: The until loop
• Internal: code examples of the read builtin command to see how you can loop over lines