更改正在运行的进程的环境

如何在env已经运行的进程中更改某些变量，例如通过/proc/PID/environ?“ file”为read-only。

需要更改或取消设置长期运行的批处理作业的DISPLAY变量，而不会终止它。

没有讨厌的黑客，您就无法做到这一点-没有API，也没有办法通知进程其环境已更改（因为这实际上是不可能的）。
即使您确实做到了这一点，也无法确保它会产生任何效果-该进程很可能已经缓存了您要戳的环境变量（因为应该没有任何东西可以更改它） ）。

如果您确实确实想这样做，并且准备好在出现问题的情况下继续工作，则可以使用调试器。例如，参见以下堆栈溢出问题：
是否可以更改另一个进程的环境变量？

实质上：

(gdb) attach process_id
(gdb) call putenv ("DISPLAY=your.new:value")
(gdb) detach

您可以尝试调用的其他可能函数是setenv或unsetenv。

请务必牢记，如果您所针对的过程对其环境块“感兴趣”，那么这可能不起作用或产生可怕的后果。首先要在非关键过程中进行测试，但要确保这些测试过程尽可能接近您要尝试的过程。

如果批处理作业可以从文件系统读取以检索更改，则无需这样做。只需运行一个具有临时唯一目录路径的作业，然后将相同路径传递给子外壳脚本即可。脚本将锁定该目录中的文件，并在锁定文件附近写入具有新值的文件。作业脚本有时会锁定相同的文件，解析并从值文件中读取更改。要查找如何在unix shell中进行锁定，只需搜索unix shell lock file或bash lock file，就已经有很多解决方案。

该解决方案的优势：

• 可在几乎任何操作系统（例如Windows或Unix）之间移植
• 只要值文件保持简单，就不需要为每个解释器（unix / windows / etc）编写和复制复杂的解析器来从文件中读取值

实施中的问题如下：

• 在外壳重定向阶段，实现依赖于文件锁（flock在Linux中要实现排除效果，在Windows中具有内置排除功能）
• 变量的每个值都是单行值（不是多行）

实施存储在这里：https : //sourceforge.net/p/contools/contools/HEAD/tree/trunk/Scripts/Tools

该bash实施：

set_vars_from_locked_file_pair.sh

#!/bin/bash

# Another variant of a configuration file variables read and set script.
# The script must stay as simple as possible, so for this task it uses these parameters:
# 1. path where to lock a lock file
# 2. path where to read a file with variable names (each per line)
# 3. path where to read a file with variable values (each per line, must be the same quantity of lines with the variable names file)

# Script can be ONLY included by "source" command.
if [[ -n "$BASH" && (-z "$BASH_LINENO" || ${BASH_LINENO[0]} -gt 0) ]]; then 

function set_vars_from_locked_file_pair()
{
  # the lock file directory must already exist
  if [[ ! -d "${1%[/\\]*}" ]]; then
    echo "$0: error: lock file directory does not exist: \`${1%[/\\]*}\`" >&2
    return 1
  fi

  if [[ ! -f "${2//\\//}" ]]; then
    echo "$0: error: variable names file does not exist: \`$2\`" >&2
    return 2
  fi

  if [[ ! -f "${3//\\//}" ]]; then
    echo "$0: error: variable values file does not exist: \`$3\`" >&2
    return 3
  fi

  function LocalMain()
  {
    # open file for direct reading by the `read` in the same shell process
    exec 7< "$2"
    exec 8< "$3"

    # cleanup on return
    trap "rm -f \"$1\" 2> /dev/null; exec 8>&-; exec 7>&-; trap - RETURN" RETURN

    local __VarName
    local __VarValue

    # shared acquire of the lock file
    while :; do
      # lock via redirection to file
      {
        flock -s 9

        # simultaneous iteration over 2 lists in the same time
        while read -r -u 7 __VarName; do
          read -r -u 8 __VarValue
          # drop line returns
          __VarName="${__VarName//[$'\r\n']}"
          __VarValue="${__VarValue//[$'\r\n']}"
          # instead of `declare -gx` because `-g` is introduced only in `bash-4.2-alpha`
          export $__VarName="$__VarValue"
          (( ${4:-0} )) && echo "$__VarName=\`$__VarValue\`"
        done

        break

        # return with previous code
      } 9> "$1" 2> /dev/null # has exclusive lock been acquired?

      # busy wait
      sleep 0.02
    done
  }

  LocalMain "${1//\\//}" "${2//\\//}" "${3//\\//}" "${4:-0}"
}

fi

测试锁

#!/bin/bash

{
  flock -x 9 2> /dev/null
  read -n1 -r -p "Press any key to continue..."
  echo >&2
} 9> "lock"

在Windows上也是如此（以可移植性为例）：

set_vars_from_locked_file_pair.bat

@echo off

rem Another variant of a configuration file variables read and set script.
rem The script must stay as simple as possible, so for this task it uses these parameters:
rem 1. path where to lock a lock file
rem 2. path where to read a file with variable names (each per line)
rem 3. path where to read a file with variable values (each per line, must be the same quantity of lines with the variable names file)

rem disable alternative variables expansion to avoid `!` character consumption
setlocal DISABLEDELAYEDEXPANSION

set "FILE_LOCK_PATH=%~1"
set "FILE_VAR_NAMES_PATH=%~2"
set "FILE_VAR_VALUES_PATH=%~3"
set "PRINT_VARS_SET=%~4"

set "FILE_LOCK_DIR=%~d1"

rem the lock file directory must already exist
if not exist "%FILE_LOCK_DIR%" (
  echo.%~nx0: error: FILE_LOCK_DIR does not exist: "%FILE_LOCK_DIR%"
  exit /b 1
) >&2

if not exist "%FILE_VAR_NAMES_PATH%" (
  echo.%~nx0: error: FILE_VAR_NAMES_PATH does not exist: "%FILE_VAR_NAMES_PATH%"
  exit /b 2
) >&2

if not exist "%FILE_VAR_VALUES_PATH%" (
  echo.%~nx0: error: FILE_VAR_VALUES_PATH does not exist: "%FILE_VAR_VALUES_PATH%"
  exit /b 3
) >&2

rem The endlocal works only in the same call context
endlocal

rem exclusive acquire of the lock file
:REPEAT_LOCK_LOOP

(
  (
    rem if lock is acquired, then we are in...
    call :MAIN "%%~2" "%%~3" "%%~4"
    call set "LASTERROR=%%ERRORLEVEL%%"

    rem exit with return code from the MAIN
  ) 9> "%~1" && (del /F /Q /A:-D "%~1" & goto EXIT)
) 2>nul

rem Busy wait: with external call significantly reduces CPU consumption while in a waiting state
pathping localhost -n -q 1 -p 20 >nul 2>&1
goto REPEAT_LOCK_LOOP

:EXIT
exit /b %LASTERROR%

:MAIN
rem drop last error
type nul>nul

if %~30 NEQ 0 goto SET_WITH_PRINT

rem trick with simultaneous iteration over 2 lists in the same time
(
  for /f "usebackq eol=# tokens=* delims=" %%i in ("%~1") do (
    set /p "%%i="
  )
) < "%~2"

exit /b 0

:SET_WITH_PRINT
rem trick with simultaneous iteration over 2 lists in the same time
(
  for /f "usebackq eol=# tokens=* delims=" %%i in ("%~1") do (
    set /p "%%i="
    rem to filter out wrong matches of a variable from the `set "%%i"`
    for /f "usebackq eol=# tokens=1,* delims==" %%j in (`set "%%i"`) do if /i "%%j" == "%%i" echo.%%i=%%k
  )
) < "%~2"

exit /b 0

测试锁

@echo off

(
  pause
) 9> ./lock

以相同的方式锁定文件来写入文件。