How to get variable from text file into Bash variable

问题

Simple question, in BASH I'm trying to read in a .pid file to kill a process. How do I read that file into a variable. All the examples I have found are trying to read in many lines. I only want to read the one file that just contains the PID

#!/bin/sh
PIDFile="/var/run/app_to_kill.pid"
CurPID=(<$PIDFile)

kill -9 $CurPID

回答1:

You're almost there:

CurPID=$(<"$PIDFile")

In the example you gave, you don't even need the temp variable. Just do:

kill -9 $(<"$PIDFile")

回答2:

POSIX portable way:

$ read pid <$pidfile

See: pid=`cat $pidfile` or read pid <$pidfile?

来源：https://stackoverflow.com/questions/8684447/how-to-get-variable-from-text-file-into-bash-variable