Linux shell编程学习笔记29：shell自带的脚本调试选项

刺骨的言语ヽ痛彻心扉 2024-02-17 09:23 15阅读 0赞

Linux shell脚本的调试方法比较多，上次我们探讨和测试了shell内建命令set所提供的一些调试选项，其实 shell 本身也提供了一些调试选项。我们以bash为例来看看。

## 1 bash 的命令行帮助信息（bash --help） ##

> purleEndurer @ csdn ~ $ bash --help  
> GNU bash, version 4.2.46(2)-release-(x86\_64-redhat-linux-gnu)  
> Usage: bash \[GNU long option\] \[option\] ...  
> bash \[GNU long option\] \[option\] script-file ...  
> GNU long options:  
> \--debug  
> \--debugger  
> \--dump-po-strings  
> \--dump-strings  
> \--help  
> \--init-file  
> \--login  
> \--noediting  
> \--noprofile  
> \--norc  
> \--posix  
> \--protected  
> \--rcfile  
> \--rpm-requires  
> \--restricted  
> \--verbose  
> \--version  
> Shell options:  
> \-irsD or -c command or -O shopt\_option (invocation only)  
> \-abefhkmnptuvxBCHP or -o option  
> Type \`bash -c "help set"' for more information about shell options.  
> Type \`bash -c help' for more information about shell builtin commands.  
> purleEndurer @ csdn ~ $

![86c927cef03b421e86c1e46aaad86243.png][]

可以看到，bash命令有很多参数和选项。

使用 `bash` 命令加上特定的选项可以在运行Shell脚本时改变其行为，帮助我们诊断问题。

## 2 bash 的内置命令set提供的选项（bash -c "help set" ） ##

我们可以使用命令 bash -c "help set" 查看 bash 内置命令set提供的选项。

> purpleEndurer @ cdu ~ $ bash -c "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.  
> purpleEndurer @ cdu ~ $

这个信息与

[Linux shell编程学习笔记28：脚本调试 set命令![icon-default.png?t=N7T8][icon-default.png_t_N7T8]https://image.dandelioncloud.cn/pgy_files/images/2024/02/06/56f2783309954a44a9e2ef81d784ed45.png][Linux shell_28_ set_icon-default.png_t_N7T8_icon-default.png_t_N7T8_https_blog.csdn.net_Purpleendurer_article_details_134506337_spm_1001.2014.3001.5501]中set --help命令显示的帮助信息是一致的。

3 查看bash内置的命令：bash -c help

> purpleEndurer @ csdn ~ $ bash -c help  
> GNU bash, version 4.2.46(2)-release (x86\_64-redhat-linux-gnu)  
> These shell commands are defined internally. Type \`help' to see this list.  
> Type \`help name' to find out more about the function \`name'.  
> Use \`info bash' to find out more about the shell in general.  
> Use \`man -k' or \`info' to find out more about commands not in this list.
> 
> A star (\*) next to a name means that the command is disabled.
> 
> job\_spec \[&\] history \[-c\] \[-d offset\] \[n\] or hist>  
> (( expression )) if COMMANDS; then COMMANDS; \[ elif C>  
> . filename \[arguments\] jobs \[-lnprs\] \[jobspec ...\] or jobs >  
> : kill \[-s sigspec | -n signum | -sigs>  
> \[ arg... \] let arg \[arg ...\]  
> \[\[ expression \]\] local \[option\] name\[=value\] ...  
> alias \[-p\] \[name\[=value\] ... \] logout \[n\]  
> bg \[job\_spec ...\] mapfile \[-n count\] \[-O origin\] \[-s c>  
> bind \[-lpvsPVS\] \[-m keymap\] \[-f filen> popd \[-n\] \[+N | -N\]  
> break \[n\] printf \[-v var\] format \[arguments\]  
> builtin \[shell-builtin \[arg ...\]\] pushd \[-n\] \[+N | -N | dir\]  
> caller \[expr\] pwd \[-LP\]  
> case WORD in \[PATTERN \[| PATTERN\]...)> read \[-ers\] \[-a array\] \[-d delim\] \[->  
> cd \[-L|\[-P \[-e\]\]\] \[dir\] readarray \[-n count\] \[-O origin\] \[-s>  
> command \[-pVv\] command \[arg ...\] readonly \[-aAf\] \[name\[=value\] ...\] o>  
> compgen \[-abcdefgjksuv\] \[-o option\] > return \[n\]  
> complete \[-abcdefgjksuv\] \[-pr\] \[-DE\] > select NAME \[in WORDS ... ;\] do COMM>  
> compopt \[-o|+o option\] \[-DE\] \[name ..> set \[-abefhkmnptuvxBCHP\] \[-o option->  
> continue \[n\] shift \[n\]  
> coproc \[NAME\] command \[redirections\] shopt \[-pqsu\] \[-o\] \[optname ...\]  
> declare \[-aAfFgilrtux\] \[-p\] \[name\[=va> source filename \[arguments\]  
> dirs \[-clpv\] \[+N\] \[-N\] suspend \[-f\]  
> disown \[-h\] \[-ar\] \[jobspec ...\] test \[expr\]  
> echo \[-neE\] \[arg ...\] time \[-p\] pipeline  
> enable \[-a\] \[-dnps\] \[-f filename\] \[na> times  
> eval \[arg ...\] trap \[-lp\] \[\[arg\] signal\_spec ...\]  
> exec \[-cl\] \[-a name\] \[command \[argume> true  
> exit \[n\] type \[-afptP\] name \[name ...\]  
> export \[-fn\] \[name\[=value\] ...\] or ex> typeset \[-aAfFgilrtux\] \[-p\] name\[=va>  
> false ulimit \[-SHacdefilmnpqrstuvx\] \[limit>  
> fc \[-e ename\] \[-lnr\] \[first\] \[last\] o> umask \[-p\] \[-S\] \[mode\]  
> fg \[job\_spec\] unalias \[-a\] name \[name ...\]  
> for NAME \[in WORDS ... \] ; do COMMAND> unset \[-f\] \[-v\] \[name ...\]  
> for (( exp1; exp2; exp3 )); do COMMAN> until COMMANDS; do COMMANDS; done  
> function name \{ COMMANDS ; \} or name > variables - Names and meanings of so>  
> getopts optstring name \[arg\] wait \[id\]  
> hash \[-lr\] \[-p pathname\] \[-dt\] \[name > while COMMANDS; do COMMANDS; done  
> help \[-dms\] \[pattern ...\] \{ COMMANDS ; \}  
> purpleEndurer @ csdn ~ $

## 2 bash 命令行常用调试选项说明和演示 ##

下面我们就bash命令行中的一些常用的调试选项逐一进行说明和演示。

### 2.1 echo $-：显示当前已启动的选项 ###

> purpleEndurer @ cdu ~ $ echo $-  
> himBH
> 
> purpleEndurer @ cdu ~ $

![0c8fe3c7768a43428465787f89799d0a.png][]

可以看到，当前启用的选项有h、i、m、B和H这几个选项处于启动状态。

### 2.2 bash -n 脚本文件名说明符：不执行脚本，仅检查错误 ###

\-n 选项的功能是：读一遍脚本中的命令但不执行，用于检查脚本中的语法等错误。

#### 2.2.1 创建测试脚本文件a.sh ####

我们用 cp 命令来创建 ，文件内容是： echo 'Hello world

为了测试，我们故意漏了命令行末尾配对的单引号。

> purleEndurer @ csdn ~ $ cp /dev/stdin a.sh  
> echo 'Hello world

![9f7f924caad044d1944ee40d85072faa.png][]

#### 2.2.2 查看测试脚本文件a.sh内容 ####

> purleEndurer @ csdn ~ $ cat a.sh  
> echo 'Hello world

![3c462324151046468a57bd0c667e2d50.png][]

#### 2.2.3 检查脚本语法错误 ####

> purleEndurer @ csdn ~ $ bash -n a.sh  
> a.sh: line 1: unexpected EOF while looking for matching \`''  
> a.sh: line 2: syntax error: unexpected end of file

![fd26b8fc23c445379d80d279f290370f.png][]

可以看到，bash检查出a.sh存在两个错误。

第1个错误出现在第1行：寻找匹配的 ''' 时出现意外的 EOF，即单引号未配对。

第2个错误出现在第2行：语法错误：意外的文件结尾。

### 2.3 bash -x 脚本文件说明符：先显示命令及参数（不显示注释），再显示执行结果 ###

bash命令的-x选项与set 命令中的-x选项功能相同，都是打开echo模式，执行命令后，会先显示该命令及所带的参数，再显示命令执行的结果：

#### 2.3.1 创建测试脚本文件a.sh ####

我们用 cp 命令来创建 a.sh，文件内容如下：

purleEndurer @ csdn ~ $ cp /dev/stdin a.sh
    echo -n Enter your name please:    # 提示用户输入名字
    read n                             # 将用户输入的名字保存到变量n                                                                            
    echo Your name is $n               # 显示用户输入的名字

![a941dfa7ea7a460f91d0da09e5b98ee1.png][]

\#号后的内容是对命令功能的说明。

#### 2.3.2 执行脚本文件a.sh ####

> purleEndurer @ csdn ~ $ bash -x a.sh  
> \+ echo -n Enter your name please:  
> Enter your name please:+ read n  
> purpleEndurer  
> \+ echo Your name is purpleEndurer  
> Your name is purpleEndurer  
> purleEndurer @ csdn ~ $

![12f5f1a36cd040d5bca754c0fa5a148d.png][]

bash会将以+开头，将执行的命令显示出来，然后再显示命令执行的结果。

#### 2.3.3 使用环境变量PS4定制显示格式 ####

其实我们在使用bash的 -x选项来显示命令和参数时前面加的 + 是环境变量PS4 保存的。

> purpleEndurer @csdn ~ $ set | grep PS4  
> PS4='+ '

![b0c8fd31cd7a4eb594dd78c2cec3c14e.png][]

因此，我们可以通过修改环境变量PS4的值来设置 bash的 -x选项显示命令和参数时的格式。

例如：我们对显示的命令和参数以 > 开头，然后引入$\{BASH\_SOURCE\} 显示脚本文件名，$\{LINENO\}显示行号，$\{FUNCNAME\[0\]\}显示正在执行的函数的名字：

> purpleEndurer @csdn ~ $ PS1="\\e\[35mpurpleEndurer\\e\[0m @csdn \\w $ "
> 
> purpleEndurer @csdn ~ $ export PS4='>$\{BASH\_SOURCE\} \[$\{LINENO\}\] $\{FUNCNAME\[0\]\}: '  
> purpleEndurer @csdn ~ $ bash -x a.sh  
> >a.sh \[1\] : echo -n Enter your name please:  
> Enter your name please:>a.sh \[2\] : read n  
> abc  
> >a.sh \[3\] : echo Your name is abc  
> Your name is abc  
> purpleEndurer @csdn ~ $

![2b95e7ff3caf4eb6a7dd1fa87e225177.png][]

如果觉得字符太多，不容易辨别的话，我们还可以分别给它们加上颜色：

> purpleEndurer @csdn ~ $ export PS4='\\e\[35m>$\{BASH\_SOURCE\} \\e\[0m \\e\[33m \[$\{LINENO\}\]\\e\[0m \\e\[31m $\{FUNCNAME\[0\]\}: \\e\[0m'  
> purpleEndurer @csdn ~ $ bash -x a.sh  
> >a.sh \[1\] : echo -n Enter your name please:  
> Enter your name please:>a.sh \[2\] : read n  
> abc  
> >a.sh \[3\] : echo Your name is abc  
> Your name is abc

![3026a4db436c4d83a49caba662687606.png][]

这里我们使用了

[Linux shell编程学习笔记4：修改命令行提示符格式（内容和颜色）![icon-default.png?t=N7T8][icon-default.png_t_N7T8]https://image.dandelioncloud.cn/pgy_files/images/2024/02/06/177f370187294660bae04108a70c2003.png][Linux shell_4_icon-default.png_t_N7T8_icon-default.png_t_N7T8_https_blog.csdn.net_Purpleendurer_article_details_133416124_spm_1001.2014.3001.5501]中介绍的知识，让脚本文件名以紫色显示，行号以黄色显示，正在执行的函数的名字以红色显示。

### 2.4 bash -v 脚本文件说明符：一边执行脚本，一边将执行过的脚本命令打印到标准输出（包括注释） ###

> purpleEndurer @csdn ~ $ export PS4='\\e\[35m>$\{BASH\_SOURCE\} \\e\[0m \\e\[33m \[$\{LINENO\}\]\\e\[0m \\e\[31m $\{FUNCNAME\[0\]\}: \\e\[0m'
> 
> purpleEndurer @csdn ~ $ bash -v a.sh  
> echo -n Enter your name please: \# 提示用户输入名字  
> Enter your name please:read n \# 将用户输入的名字保存到变量n  
> abc  
> echo Your name is $n \# 显示用户输入的名字  
> Your name is abc  
> purpleEndurer @csdn ~ $

![a7d3120c3c27485a8a54ee400f242420.png][]

可以看到，-v选项显示所执行的命令不受环境变量PS4的影响，而且会连脚本文件中的注释一并显示。

[86c927cef03b421e86c1e46aaad86243.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/06/227069d5ded44683a9e5ecf56e06b112.png
[icon-default.png_t_N7T8]: https://csdnimg.cn/release/blog_editor_html/release2.3.6/ckeditor/plugins/CsdnLink/icons/icon-default.png?t=N7T8
[Linux shell_28_ set_icon-default.png_t_N7T8_icon-default.png_t_N7T8_https_blog.csdn.net_Purpleendurer_article_details_134506337_spm_1001.2014.3001.5501]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/06/56f2783309954a44a9e2ef81d784ed45.png
[0c8fe3c7768a43428465787f89799d0a.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/06/31d2fb5e88bf47cc854c6d9ef03cbd9d.png
[9f7f924caad044d1944ee40d85072faa.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/06/4516fd1c79d4471ea772d26cf4bc4685.png
[3c462324151046468a57bd0c667e2d50.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/06/89cbf2c92ed047eb9de5728c9213bdb7.png
[fd26b8fc23c445379d80d279f290370f.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/06/6a0f7f39b2e74b288cdc93f3806f3216.png
[a941dfa7ea7a460f91d0da09e5b98ee1.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/06/45b08f0796a4444fba95022fb9d115eb.png
[12f5f1a36cd040d5bca754c0fa5a148d.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/06/abeee7342a5e4ed0b021174a8d0604aa.png
[b0c8fd31cd7a4eb594dd78c2cec3c14e.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/06/d8c952269b8645aab38abe6feb0adca8.png
[2b95e7ff3caf4eb6a7dd1fa87e225177.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/06/2901f01830af4c9fb822f4e3983d1db1.png
[3026a4db436c4d83a49caba662687606.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/06/54e4062521304a048c858075a2af12ca.png
[Linux shell_4_icon-default.png_t_N7T8_icon-default.png_t_N7T8_https_blog.csdn.net_Purpleendurer_article_details_133416124_spm_1001.2014.3001.5501]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/06/177f370187294660bae04108a70c2003.png
[a7d3120c3c27485a8a54ee400f242420.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/06/a07438f24ea7499c92f4f5a04857dd89.png