Difference between wait and sleep

Question

What is difference between wait and sleep?

score 439 · Accepted Answer · edited Oct 09 '17 at 13:14

439

wait waits for a process to finish; sleep sleeps for a certain amount of seconds.

edited Oct 09 '17 at 13:14

arc

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answered Nov 08 '12 at 20:08

MRAB

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`wait 60` waits for job 60 to finish; `sleep 60` sleeps for 60 seconds. – Colin Pitrat Aug 03 '16 at 10:59
`wait 60` should finish immediately with an error message; if not, you're doing something wrong. – PoolloverNathan Mar 15 '23 at 18:39

kbulgrien · Answer 2 · 2018-05-10T16:57:53.780

wait is a BASH built-in command. From man bash:

    wait [n ...]
        Wait  for each specified process and return its termination sta-
        tus.  Each n may be a process ID or a job  specification;  if  a
        job  spec  is  given,  all  processes in that job's pipeline are
        waited for.  If n is not given, all currently active child  pro-
        cesses  are  waited  for,  and  the return status is zero.  If n
        specifies a non-existent process or job, the  return  status  is
        127.   Otherwise,  the  return  status is the exit status of the
        last process or job waited for.

sleep is not a shell built-in command. It is a utility that delays for a specified amount of time.

The sleep command may support waiting in various units of time. GNU coreutils 8.4 man sleep says:

    SYNOPSIS
        sleep NUMBER[SUFFIX]...

    DESCRIPTION
        Pause for NUMBER seconds.  SUFFIX may be ‘s’ for seconds (the default),
        ‘m’ for minutes, ‘h’ for hours or ‘d’ for days.  Unlike most  implemen-
        tations  that require NUMBER be an integer, here NUMBER may be an arbi-
        trary floating point number.  Given two or more  arguments,  pause  for
        the amount of time specified by the sum of their values.

score 110 · Answer 3 · edited Jun 26 '19 at 08:01

110

sleep just delays the shell for the given amount of seconds.

wait makes the shell wait for the given job. e.g.:

workhard &
[1] 27408
workharder &
[2] 27409
wait %1 %2

delays the shell until both of the subprocesses have finished

edited Jun 26 '19 at 08:01

iBug

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answered Nov 08 '12 at 20:10

pbhd

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IMHO it is `wait %1 %2` or `wait 27408 27409` or simply `wait` if there is no other background process. In this case you are trying to wait for PID 1 (init) and PID 2 ([migration/0] on my Linux), but you will get error message, like: `-bash: wait: pid 1 is not a child of this shell` and returns the exit code `127`. – TrueY Nov 19 '14 at 08:54
15

So as of 2 Years nobody realized it. You are absolutely right, will edit the answer... – pbhd Nov 19 '14 at 09:02

Difference between wait and sleep

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