The sleep Command in Linux: Pause a Script for Seconds, Minutes or Hours

Applies to: Linux: GNU coreutils 9.7 (Debian 13), uutils coreutils 0.8.0 (Ubuntu 26.04) and BusyBox 1.37 (Alpine 3.24); tested on all three

sleep pauses for the time you give it, then exits. sleep 5 waits five seconds. Add a suffix for other units: s seconds, m minutes, h hours, d days. It is mostly used in shell scripts: to wait between retries, to space out requests or to wait for something to start.

Syntax and examples

sleep 5          # 5 seconds
sleep 0.5        # half a second
sleep 2m         # 2 minutes
sleep 1h         # 1 hour
sleep 1m 30s     # several values are added: 90 seconds
sleep infinity   # wait until the process is stopped

Fractions such as 0.5 and several values work in all three versions we tested. Only POSIX’s basic form, one whole number of seconds without a suffix, is guaranteed on every Unix system, so use that in scripts that must also run on other systems.

You can check the pause with time:

$ time sleep 1.5

real	0m1.507s
user	0m0.000s
sys	0m0.001s

sleep prints nothing and returns exit code 0 when the time is up. Press Ctrl+C to stop it early.

Error messages

$ sleep 5x
sleep: invalid time interval '5x'
Try 'sleep --help' for more information.
$ sleep
sleep: missing operand
Try 'sleep --help' for more information.

Both return exit code 1. Don’t put a space between the number and the unit: sleep 5 m fails with invalid time interval 'm', because m is read as a second value. BusyBox words the error as sleep: invalid number '5x'.

Use sleep in a script

Retry something a few times with a pause:

for i in 1 2 3; do
  echo "attempt $i"
  some_command && break
  sleep 10
done

Wait until a file appears (or a service answers), checking every second:

until [ -f /tmp/ready ]; do
  echo "waiting"
  sleep 1
done
echo "ready"

Run a check forever, every 30 seconds:

while true; do
  date >> /var/log/mycheck.log
  sleep 30
done

A random delay in cron

To stop many servers running the same cron job at exactly the same second, add a random wait of up to a minute before the command:

*/15 * * * * sleep $(shuf -i 0-59 -n 1); /usr/local/bin/backup.sh

Use shuf rather than $RANDOM here. Cron runs commands with sh, which is dash on Debian and Ubuntu, and dash has no $RANDOM: in our test $((RANDOM % 60)) always gave 0 in dash but a random number in Bash.

Related commands

• timeout 10 some_command: stops a command if it runs longer than 10 seconds (exit code 124 when it had to stop it).
• wait: waits until the background jobs started in the script (command &) are finished, instead of guessing a time with sleep.
• read -t 10: waits up to 10 seconds for the user to press Enter, then carries on (Bash; the exit code is above 128 when the time ran out).

Which sleep you have

sleep is a separate program, not a Bash built-in (type sleep shows /usr/bin/sleep). Debian 13 uses GNU coreutils. Ubuntu 26.04 uses the Rust rewrite, uutils coreutils (sleep --version shows sleep (uutils coreutils) 0.8.0); the GNU version is still installed as gnusleep. Everything on this page behaved the same with both.

More scripting help: Bash functions, cron jobs and crontab syntax and running a command in the background.

Official documentation: GNU sleep and sleep(1).