解释bash脚本中set -e与set -o pipefail的作用-白红宇

解释bash脚本中set -e与set -o pipefail的作用

阅读量：4176 次

发布时间：2019-05-26

本文共 2488 字，大约阅读时间需要 8 分钟。

man set中的解释：

set [--abefhkmnptuvxBCEHPT] [-o option] [arg ...]

set [+abefhkmnptuvxBCEHPT] [+o option] [arg ...]

... ...

-e Exit immediately if a pipeline (which may consist of a

single simple command), a subshell command enclosed in

parentheses, or one of the commands executed as part of

a command list enclosed by braces (see SHELL GRAMMAR

above) exits with a non-zero status. The shell does not

exit if the command that fails is part of the command

list immediately following a while or until keyword,

part of the test following the if or elif reserved

words, part of any command executed in a && or ││ list

except the command following the final && or ││, any

command in a pipeline but the last, or if the command’s

return value is being inverted with !. A trap on ERR,

if set, is executed before the shell exits. This option

applies to the shell environment and each subshell envi-

ronment separately (see COMMAND EXECUTION ENVIRONMENT

above), and may cause subshells to exit before executing

all the commands in the subshell.

... ...

-o option-name

The option-name can be one of the following:

... ...

pipefail

If set, the return value of a pipeline is the

value of the last (rightmost) command to exit

with a non-zero status, or zero if all commands

in the pipeline exit successfully. This option

is disabled by default.

.. ...

个人理解：

set -e表示一旦脚本中有命令的返回值为非0，则脚本立即退出，后续命令不再执行;

set -o pipefail表示在管道连接的命令序列中，只要有任何一个命令返回非0值，则整个管道返回非0值，即使最后一个命令返回0.

小实验：

#!/bin/bash# testset.shecho 'disable exit on non-zero return status and pipefail track'set +eset +o pipefaila=$[1/0]|b=2echo 'return status = '$?echo 'disable exit on non-zero return status but enable pipefail track'set +eset -o pipefaila=$[1/0]|b=2echo 'return status = '$?echo 'enable exit on non-zero return status and pipefail track'set -eset -o pipefaila=$[1/0]|b=2echo 'return status = '$?

输出结果：

[root@desktop2 ~]# ./testset.sh

disable exit on non-zero return status and pipefail track

./testset.sh: line 6: 1/0: division by 0 (error token is "0")

return status = 0

disable exit on non-zero return status but enable pipefail track

./testset.sh: line 12: 1/0: division by 0 (error token is "0")

return status = 1

enable exit on non-zero return status and pipefail track

./testset.sh: line 18: 1/0: division by 0 (error token is "0")

[root@desktop2 ~]#

REF: