如何使用bash/shell更改argv [0]值? [英] How to change argv[0] value using bash/shell?

问题描述

该脚本应该能够在shell/bash脚本中更改argv [0]的值.我在较旧的帖子上找到了，但无法真正理解它在做什么.有人可以解释一下这条线是如何工作的:

  sh -c.'$ 0'" argv0new"$ @" 

测试.$ INNERCALL" 也是变量吗?

原始问题:如何更改argv在shell/bash脚本中[0]值?

 #！/bin/bash#尝试使用几个参数执行此脚本以查看效果测试.$ INNERCALL" = .YES ||{出口INNERCALL = YES#此方法适用于shell和bash解释器sh -c.'$ 0'" argv0new"$ @"#bash -c.'$ 0'" argv0new"$ @"退出$?}printf"argv [0] = $ 0 \ n"i = 1;为"$ @"中的arg；做printf"argv [$ i] = $ arg \ n";i =`expr $ i + 1`;完成 

解决方案

让我们逐行浏览

测试.$ INNERCALL" =.是

基本上，这可以查看 $ INNERCALL 中是否已经有值 YES .Shell的" 函数以一种安全的方式进行变量扩展，并将其全部编组为一个值，例如

  foo ="hello"bar =，世界！"回声"foobar是:$ foo $ bar" 

打印 foobar是:您好，世界！

---

  ||{...} 

这使用 ||| 运算符来表示，如果先前的程序返回的值非零(例如测试是一个程序，如果关联的条件为false，则返回1，然后执行此代码块，否则跳过它(请参见

这就是魔术发生的地方. sh -c 打开一个新的shell，然后从后面的字符串中读取其参数..'$ 0'" 对当前位于 $ 0 的值使用 sh 的源函数，该值应该是当前文件./p>

基本上 sh -c.'$ 0'" 只是在子 sh 进程中再次打开当前文件，然后其余行替换参数: argv0new 成为新的$ 0，并且还通过包含"$ @"

来保留文件的原始参数

然后 exit $?返回子进程运行的任何返回值.

其余代码只是为了证明除 $ 0 以外的所有参数都相同，并且已替换 $ 0 .

---

tl; dr ，它将打开一个子shell进程，告诉它读取当前文件，替换参数，然后导出测试值，以使其不会无限循环.

tl; dr >

The script should be able to change argv[0] value in shell / bash script. I found on an older post but couldn't really understand what it is doing. Could someone please explain how the line works:

sh -c ". '$0'" argv0new "$@"

Also is test ".$INNERCALL" meant to be a variable ?

Original question: How to change argv[0] value in shell / bash script?

#! /bin/bash    # try executing this script with several arguments to see the effect

test ".$INNERCALL" = .YES || {
    export INNERCALL=YES
    # this method works both for shell and bash interpreters
    sh -c ". '$0'" argv0new "$@"
    # bash -c ". '$0'" argv0new "$@"
    exit $?
}

printf "argv[0]=$0\n"
i=1 ; for arg in "$@" ; do printf "argv[$i]=$arg\n" ; i=`expr $i + 1` ;done

解决方案

Let's go through this line by line

test ".$INNERCALL" = .YES

basically this sees if $INNERCALL already has the value YES in it. Shell's "" function does variable expansion in a safe way, and marshalls it all into a value, e.g.

foo="hello"
bar=", world!"
echo "foobar is: $foo$bar"

prints foobar is: hello, world!

---

|| {
...
}

This uses the || operator to say, if the previous program returned with a non-zero value (e.g. test is a program that returns 1 if the associated conditional is false), then execute this code block, otherwise skip it (see this link for more on ||)

---

export INNERCALL=YES

This sets INNERCALL to YES, which means that this only executes for the first level

---

sh -c ". '$0'" argv0new "$@"
exit $?

This is where the magic happens. sh -c opens a new shell, which then reads its arguments from the string that follows. ". '$0'" uses sh's source function on the value currently at $0, which is supposed to be this current file.

Basically sh -c ". '$0'" just opens the current file again in a child sh process, then the rest of the line replaces the arguments: argv0new becomes the new $0, and you keep the original arguments to the file by also including "$@"

then exit $? returns whatever return value the child process runs.

the rest of the code is just to prove that all of the arguments except for $0 is the same, and $0 has been replaced.

---

tl;dr it opens up a child shell process, tells it to read the current file, replaces the arguments, and then exports a test value so that it doesn't infinite loop.

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