csh脚本作为可执行文件不设置 [英] csh script as executable does not setenv

问题描述

我无法通过可执行文件 csh / tcsh 脚本

$ b设置 env 变量
$ b

一个 env 在中设置变量csh / tcsh 可执行脚本myscript

脚本的内容...

  setenv MYVAR / abc / xyz 
  

它不能在shell上设置并报告Undefined variable

我已将 csh / tcsh 脚本通过以下shell命令

  chmod + x / home / xx / bin / myscript 
  

也将路径更新为

  set path =（/ home / xx / bin $ path）
 which myscript 
 / home / xx / bin / myscript 
  

当我在命令行上运行脚本并回应env变量。

  myscript 
 echo $ MYVAR 
 MYVAR未定义的变量
  

但是如果我以逗号来源d行

  source / home / xx / bin / myscript 
 echo $ MYVAR 
 / abc / xyz 
  

解决方案

这不是环境变量的工作原理。 >

为进程（在这种情况下为 tcsh ）设置环境变量，该进程传递给所有子进程。所以当你这样做：

  $ setenv LS_COLORS = foo 
 $ ls 
  

您首先为 tcsh LS_COLORS c>进程， tcsh 然后启动子进程 ls ，其中包含 tcsh 的环境（包括 LS_COLORS ），然后可以使用。

然而，重新设置环境是一个子进程，然后想要传播回父进程（不知何故）。这不可能。这与 tcsh 无关，它对系统上的任何进程都是这样。

它适用于 source 因为 source 读取一个文件，并在当前进程中逐行执行。所以它不会启动一个新的 tcsh 进程。

我会把它作为一个练习给你什么这意味着如果它可以可能:-)你真的想处理设置一些随机环境变量的不明智的shell脚本吗？而由 php 进程设置的环境变量怎么样，我们希望这些变量返回到父 httpd 进程中？ ： - ）

---

您没有真正描述您要实现的目标 ，但一般来说，您想要执行以下操作：

 ＃！/ bin / csh -f 
 
＃...做东西... 
 
 echo请将此行复制到您的环境中：
 echosetenv MYVAR $ myvar
  

I am not able to set env variables through an executable csh/tcsh script

An env variable set inside a csh/tcsh executable script "myscript"

contents of the script ...

setenv MYVAR /abc/xyz

which is not able to set on the shell and reports "Undefined variable"

I have made the csh/tcsh script as executable by the following shell command

chmod +x /home/xx/bin/myscript

also the path is updated to

set path = (/home/xx/bin $path)    
which myscript    
/home/xx/bin/myscript

When I run the script on command line and echo the env variable ..

myscript
echo $MYVAR
MYVAR "Undefined variable"

but if i source on command line

source /home/xx/bin/myscript
echo $MYVAR
/abc/xyz

解决方案

This is not how environment variables work.

An environment variable is set for a process (in this case, tcsh) which is passed on to all child processes. So when you do:

$ setenv LS_COLORS=foo
$ ls

You first set LS_COLORS for the tcsh process, tcsh then starts the child process ls which inheres tcsh's environment (including LS_COLORS), which it can then use.

However, what you're doing is setting the environment is a child process, and then want to propagate this back to the parent process (somehow). This is not possible. This has nothing to do with tcsh, it works like this for any process on the system.

It works with source because source reads a file, and executes it line-by-line in the current process. So it doesn't start a new tcsh process.

I will leave it as an exercise to you what the implications would mean if it would be possible :-) Do you really want to deal with unwise shell scripts that set some random environment variables? And what about environment variables set by a php process, do we want those to go back in the parent httpd process? :-)

---

You didn't really describe what goal you're trying to achieve, but in general, you want to do something like:

#!/bin/csh -f                                                               

# ... Do stuff ...                                                          

echo "Please copy this line to your environment:"
echo "setenv MYVAR $myvar"

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