使用 ps 检查正在运行的脚本的数量
我正在编写一个脚本（show_volume.sh），该脚本可能会在短时间内被调用多次。我需要一种方法来确定该脚本是否有多个正在运行的实例。我想我可以使用ps，所以我在Bash中编写了这个函数：
is_only_process(){
PCOUNT=`ps -a | grep show_volume.sh | wc -l`
echo $PCOUNT
if (( PCOUNT==1 )); then
return 1
fi
return 0
}
所以我添加了这两行
is_only_process
sleep 4
并启动了这个脚本一次，但是echo $PCOUNT的输出没有对我来说有任何意义。我总是得到值 2，而不是预期的 1。当我运行此命令时
ps -a | grep show_volume.sh | | grep show_volume.sh | 当脚本运行时，我从另一个终端接收
到值 1。 当我连续运行这个脚本几次时，情况几乎是一样的，例如使用 for 循环运行 10 次。当我使用另一个终端时收到正确的值时，脚本本身会确定过高的值。
现在，为什么这个脚本要确定这些奇数值？
I'm writing a script (show_volume.sh) which may be called several times in short intervals. I need a way to determine whether there is more than just one running instance of this script. I figured I could use ps, so I wrote this function in Bash:
is_only_process(){
PCOUNT=`ps -a | grep show_volume.sh | wc -l`
echo $PCOUNT
if (( PCOUNT==1 )); then
return 1
fi
return 0
}
So I added these 2 lines
is_only_process
sleep 4
and started this script once, but the output of echo $PCOUNT does not make any sense to me. I always get the value 2, not 1, as expected. When I run this command
ps -a | grep show_volume.sh | wc -l
from another terminal while the script is running, I receive the value 1.
It's pretty much the same when I run this script several times in a row, e.g. 10 times using a for loop. The script itself determines values which are too high while I receive correct values when using another terminal.
Now, why does this script determine these odd values?
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此时
ps运行一个进程grep show_volume.sh也在运行，所以你总是数grep！简单的解决方案，
grep s[h]ow_volume.sh。 grep（不是 shell）会将[h]折叠为h并搜索你想要的内容，但是你的 grep 不会匹配自身，因为它会有 []参数。pgrep对于此任务也很有用，并且足够聪明，可以始终排除自身。At the moment
psruns a processgrep show_volume.shis also running, so you always count the grep!Simple solution,
grep s[h]ow_volume.sh. The grep (not shell) will collapse the[h]tohand search for what you want, but your grep won't match itself because it will have [] in the parameter.pgrepis also useful for this task and is smart enough to always exclude itself.如果您以不同用户身份运行脚本，则
ps -a将仅显示当前用户的实例，并且仅显示带有附加终端的实例。使用ps -ax或ps -e。将显示计数，而无需使用
wc。If you're running the script as different users then
ps -awill only show instances for the current user and only those with an attached terminal. Useps -axorps -e.will show a count without having to use
wc.尝试排除 grep 以及，因为你的 grep 本身也包含
show_volume.sh，一个例子Try to exclude grep as well, as your grep itself also contains
show_volume.sh, an exampleajreal提供的解决方案：
ps -a | grep show_volume.sh | | grep show_volume.sh | grep -v grep | grep -v wc -l
应该可以工作。如果没有，请提供
ps -a | 的输出grep show_volume.sh | | grep show_volume.sh | grep -v grep
在这里
The solution provided by ajreal:
ps -a | grep show_volume.sh | grep -v grep | wc -l
should work. If it does not, please provide output of
ps -a | grep show_volume.sh | grep -v grep
here