LANGUAGE » SHELL_SCRIPT » BASH » FLOW_CONTROL

Loop

Last updated:

While syntax ​

bash
while condition; do
  do_domething
done

For syntax ​

bash
for i in {1..10}; do
  echo $i
done

for MYVAR in val1 val2 val3; do
  echo $MYVAR
done

for path in folder/*/; do
  echo ${path}
  echo ${path%?}  # Remove last character
done

Examples ​

Loop until user signal:

bash
terminate=0
trap abort SIGUSR1

abort() {
  echo "Program has been aborted."
  terminate=1
}

while [[ terminate -eq 0 ]]; do
  stuff
done

Loop a variable using newline as separator.

bash
while IFS='' read -r line || [[ -n "${line}" ]]; do
  echo $line
done <<< "${message}"

Loop a variable using ; as separator (using IFS='' may add newline to the last variable).

bash
while read -rd ';' i || [[ -n "${i}" ]]; do
  echo "Value $i"
done <<< "1;2;3"