set命令簡介
使用內置命令set可以調試Shell腳本的指定部分。
set命令通過選項開關來設置shell的不同特性，每個特性都對應一個選項。
set -<Options>直接啟用指定選項set +<Options>直接停用指定選項set -o <option-name>通過選項名啟用對應的選項set +o <option-name>通過選項名停用對應的選項
常用命令
-
set -o輸出當前set選項的配置情況 -
set +o以set命令形式輸出當前set選項的配置情況 -
set -x或者set -o xtrace啟用跟蹤（調試）模式，識別語法錯誤和邏輯錯誤，顯示所有執行的命令、參數和結果 -
set -v或者set -o verbose啟用詳細模式，將所有執行過的腳本命令打印到標准輸出 -
set -n或者set -o noexec語法檢查模式，讀取腳本並檢查語法錯誤，但不執行 -
set -e或者set -o errexit如果命令運行失敗，腳本立即退出執行 -
set -u或者set -o nounset如果存在未聲明（賦值）的變量，腳本立即退出執行（交互式shell不退出） -
set -o pipefail
the return value of a pipeline is the status of the last command to exit with a non-zero status,
or zero if no command exited with a non-zero status
簡而言之，就是如果命令執行失敗就返回非0值，如果所有命令都成功則返回0值。
命令幫助
[root@anliven ~]# help set
set: set [-abefhkmnptuvxBCHP] [-o option-name] [--] [arg ...]
Set or unset values of shell options and positional parameters.
Change the value of shell attributes and positional parameters, or
display the names and values of shell variables.
Options:
-a Mark variables which are modified or created for export.
-b Notify of job termination immediately.
-e Exit immediately if a command exits with a non-zero status.
-f Disable file name generation (globbing).
-h Remember the location of commands as they are looked up.
-k All assignment arguments are placed in the environment for a
command, not just those that precede the command name.
-m Job control is enabled.
-n Read commands but do not execute them.
-o option-name
Set the variable corresponding to option-name:
allexport same as -a
braceexpand same as -B
emacs use an emacs-style line editing interface
errexit same as -e
errtrace same as -E
functrace same as -T
hashall same as -h
histexpand same as -H
history enable command history
ignoreeof the shell will not exit upon reading EOF
interactive-comments
allow comments to appear in interactive commands
keyword same as -k
monitor same as -m
noclobber same as -C
noexec same as -n
noglob same as -f
nolog currently accepted but ignored
notify same as -b
nounset same as -u
onecmd same as -t
physical same as -P
pipefail the return value of a pipeline is the status of
the last command to exit with a non-zero status,
or zero if no command exited with a non-zero status
posix change the behavior of bash where the default
operation differs from the Posix standard to
match the standard
privileged same as -p
verbose same as -v
vi use a vi-style line editing interface
xtrace same as -x
-p Turned on whenever the real and effective user ids do not match.
Disables processing of the $ENV file and importing of shell
functions. Turning this option off causes the effective uid and
gid to be set to the real uid and gid.
-t Exit after reading and executing one command.
-u Treat unset variables as an error when substituting.
-v Print shell input lines as they are read.
-x Print commands and their arguments as they are executed.
-B the shell will perform brace expansion
-C If set, disallow existing regular files to be overwritten
by redirection of output.
-E If set, the ERR trap is inherited by shell functions.
-H Enable ! style history substitution. This flag is on
by default when the shell is interactive.
-P If set, do not follow symbolic links when executing commands
such as cd which change the current directory.
-T If set, the DEBUG trap is inherited by shell functions.
-- Assign any remaining arguments to the positional parameters.
If there are no remaining arguments, the positional parameters
are unset.
- Assign any remaining arguments to the positional parameters.
The -x and -v options are turned off.
Using + rather than - causes these flags to be turned off. The
flags can also be used upon invocation of the shell. The current
set of flags may be found in $-. The remaining n ARGs are positional
parameters and are assigned, in order, to $1, $2, .. $n. If no
ARGs are given, all shell variables are printed.
Exit Status:
Returns success unless an invalid option is given.
[root@anliven ~]#
命令示例
[root@anliven ~]# set -o
allexport off
braceexpand on
emacs on
errexit off
errtrace off
functrace off
hashall on
histexpand on
history on
ignoreeof off
interactive-comments on
keyword off
monitor on
noclobber off
noexec off
noglob off
nolog off
notify off
nounset off
onecmd off
physical off
pipefail off
posix off
privileged off
verbose off
vi off
xtrace off
[root@anliven ~]#
[root@anliven ~]# set +o
set +o allexport
set -o braceexpand
set -o emacs
set +o errexit
set +o errtrace
set +o functrace
set -o hashall
set -o histexpand
set -o history
set +o ignoreeof
set -o interactive-comments
set +o keyword
set -o monitor
set +o noclobber
set +o noexec
set +o noglob
set +o nolog
set +o notify
set +o nounset
set +o onecmd
set +o physical
set +o pipefail
set +o posix
set +o privileged
set +o verbose
set +o vi
set +o xtrace
[root@anliven ~]#
其他執行shell腳本調試的方法
- 在命令行提供參數，調試整個腳本，例如
$bash -x script.sh - 腳本開頭提供參數，調試整個腳本，例如
#!/bin/bash -x
參考信息
- Bash 腳本 set 命令教程：http://www.ruanyifeng.com/blog/2017/11/bash-set.html