Bash set +x 而不打印
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Bash set +x without it being printed
提问by Andreas Spindler
Does anyone know if we can say set +xin bash without it being printed:
有谁知道我们是否可以set +x在不打印的情况下用 bash说：
set -x
command
set +x
traces
痕迹
+ command
+ set +x
but it should just print
但它应该只是打印
+ command
Bash is Version 4.1.10(4). This is bugging me for some time now - output is cluttered with useless set +xlines, making the trace facility not as useful as it could be.
Bash 是版本 4.1.10(4)。这让我困扰了一段时间 - 输出中充斥着无用的set +x线条，使跟踪工具变得不那么有用。
回答by McJoey
I had the same problem, and I was able to find a solution that doesn't use a subshell:
我遇到了同样的问题，我找到了一个不使用子shell的解决方案：
set -x
command
{ set +x; } 2>/dev/null
回答by choroba
You can use a subshell. Upon exiting the subshell, the setting to xwill be lost:
您可以使用子shell。退出子shell后，设置x将丢失：
( set -x ; command )
回答by user108471
I hacked up a solution to this just recently when I became annoyed with it:
最近，当我对此感到恼火时，我想出了一个解决方案：
shopt -s expand_aliases
_xtrace() {
case in
on) set -x ;;
off) set +x ;;
esac
}
alias xtrace='{ _xtrace $(cat); } 2>/dev/null <<<'
This allows you to enable and disable xtrace as in the following, where I'm logging how the arguments are assigned to variables:
这允许您启用和禁用 xtrace，如下所示，我正在记录参数如何分配给变量：
xtrace on
ARG1=
ARG2=
xtrace off
And you get output that looks like:
你会得到如下输出：
$ ./script.sh one two
+ ARG1=one
+ ARG2=two
回答by Oliver
How about a solution based on a simplified version of @user108471:
基于@user108471的简化版本的解决方案怎么样：
shopt -s expand_aliases
alias trace_on='set -x'
alias trace_off='{ set +x; } 2>/dev/null'
trace_on
...stuff...
trace_off
回答by user3286792
This is a combination of a few ideas that can enclose a block of code and preserves the exit status.
这是几个想法的组合，可以包含一个代码块并保留退出状态。
#!/bin/bash
shopt -s expand_aliases
alias trace_on='set -x'
alias trace_off='{ PREV_STATUS=$? ; set +x; } 2>/dev/null; (exit $PREV_STATUS)'
trace_on
echo hello
trace_off
echo "status: $?"
trace_on
(exit 56)
trace_off
When executed:
执行时：
$ ./test.sh
+ echo hello
hello
status: 0
+ exit 56
status: 56
