Shell, exit the entire script

General Practice

Cat>test.SH<<eof"'#!/bin/Bashexit_script () {Exit1}Echo "before Exit"Exit_scriptEcho "After exit"EOFchmodA+x test.SH./test.SHEcho$?# output before exit1

You can see that direct use exit can exit the script, and you can pass the error code as an argument. Let's make a little change to the script.

Problems that exist

Cat>test.SH<<eof"'#!/bin/Bashexit_script () {Exit1}Echo "before Exit":|Exit_scriptEcho "After exit"EOFchmodA+x test.SH./test.SHEcho$?# Output before Exitafter exit0

管道(|)executing a exit_script function in, does not exit the entire script! The reason is that you exit can only exit it Shell , and the 管道 command/function that is executed in is executed in isolation Shell(Sub-Shell) , so the process tree of the above script looks like this:

PPID PID pgid SID TTY tpgid STAT UID time COMMAND17510269592695926959 pts/014049 Ss00:XX \_-bash26959138431384326959 pts/0 14049 S 0 0:00 | \_/bin/bash./test.sh138431384413843 26959 pts/0 14049 S 0 0:xx | | \_:13843 13845 13843   26959 PTS
                                 
                                  /0 14049 S 0 0:00 | | \_/bin
                                  /bash./test.sh13845 13846 13843 26959 pts/0 14049 S 0 0:00 | | \ _ Exit 1           
                                      

From the top down, the meanings of each PID are shown in the following table:

pid	< Span style= "FONT-SIZE:16PX;" > description
26959	. The shell where/test.sh resides
13843	In the pipeline: the newly opened shell
13844	: command
13845	Exit_shell newly opened Shell in the pipeline
13846	Exit command

Use trapAnd killExit the entire script

Cat>test.SH<<eof"'#!/bin/Bashexport top_pid=$ $trap'Exit 1'Termexit_script () {Kill-s term $TOP _pid}Echo "before Exit":|Exit_scriptEcho "After exit"EOFchmodA+x test.SH./test.SHEcho$?# output before exit1

Here is the first signal in the main process of the script 捕获(trap) TERM : When the main process receives the TERM signal, it executes, and exit 1 then sends a signal to the Sub-Shell script master process TERM , so that the entire script can be exited!

Shell, exit the entire script