Advanced Bash−Scripting Guide

for b in 1 2 3 4 5
do
echo "Pass $inner in inner loop."
let "inner+=1" # Increment inner loop counter.
done
# End of inner loop.
let "outer+=1" # Increment outer loop counter.
echo
# Space between output in pass of outer loop.
done
# End of outer loop.
exit 0
Advanced Bash−Scripting Guide
See Example 26−6 for an illustration of nested "while" loops, and Example 26−7 to see a "while" loop nested
inside an "until" loop.
10.3. Loop Control
Commands Affecting Loop Behavior
break, continue
The break and continue loop control commands [23] correspond exactly to their counterparts in other
programming languages. The break command terminates the loop (breaks out of it), while continue
causes a jump to the next iteration of the loop, skipping all the remaining commands in that particular
loop cycle.
Example 10−20. Effects of break and continue in a loop
#!/bin/bash
LIMIT=19 # Upper limit
echo
echo "Printing Numbers 1 through 20 (but not 3 and 11)."
a=0
while [ $a −le "$LIMIT" ]
do
a=$(($a+1))
if [ "$a" −eq 3 ] || [ "$a" −eq 11 ] # Excludes 3 and 11
then
continue # Skip rest of this particular loop iteration.
fi
echo −n "$a "
done
# Exercise:
# Why does loop print up to 20?
echo; echo
echo Printing Numbers 1 through 20, but something happens after 2.
Chapter 10. Loops and Branches 114