等待和睡眠的区别

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最佳答案

wait等待进程完成;sleep休眠一定的秒数。

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wait是BASH内置命令。从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不是shell内置命令。它是一个延迟指定时间的实用程序。

sleep命令可以支持不同时间单位的等待。GNU coreutils 8.4 man sleep说:

    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.

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sleep只是将shell延迟给定的秒数。

wait使shell等待给定的作业。例如:

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

延迟shell，直到两个子进程都完成