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启用 shopt autocd 时隐藏“cd something”

tag-icon • tag-icon command-line bash
启用 shopt autocd 时隐藏“cd something”

当shopt -s autocd我导航到任何文件夹（例如文件~/Projects夹）时，我会cd ~/Projects进入终端输出，然后移动到~/Projects。我怎样才能隐藏刚刚执行的输出shopt？（cd ~/Projects事情）：截图

答案1

此输出（以及许多其他自动生成的 Bash 输出）被发送到 set -x 使用的相同文件描述符，因此您可以使用：

exec {BASH_XTRACEFD}>/dev/null

将其重定向到/dev/null。

然而，这似乎将文件描述符泄漏到所有执行的进程中，这可能是不可取的。（我对此感到有点惊讶……我原以为 BASH_XTRACEFD 文件描述符会被标记为 close-on-exec。）

我发现这里但我不确定这种重定向的后果，也不知道如何逆转它

答案2

如果有人想使用BASH_XTRACEFD重定向技巧，但保留的行为set -x，这就是我所做的：

shopt -s autocd

# silence_autocd
# - Hack to stop autocd from printing the directory after autocd'ing.
# - Unfortunately there is no clean way to do this except messing with
#   BASH_XTRACEFD, a poorly understood file descriptor that we are better not
#   to mess with, yet here we are.
# - Warning: This might break things, so try disabling it if something looks
#   off.
silence_autocd() {
  exec {BASH_XTRACEFD}>/dev/null
}

silence_autocd

# unsilence_autocd 
# - Needed to undo the above temporarily.
# - Unfortunately, BASH_XTRACEFD is used for other things besides autocd.
# - In those cases, I need to undo and redo the redirection.
# - Currently "set -x" is the only notable user of BASH_XTRACEFD that I've
#   found so far, but there could be others in the future.
# - For the time being, I pray to the Bash Gods to provide a native way to
#   disable autocd printing soon.
unsilence_autocd() {
  exec {BASH_XTRACEFD}>/dev/stdout
}

# custom set
function set () {
  # if calling "set -x", undo the silencing of autocd
  if [[ "$#" == 1 && "$1" == "-x" ]]; then
    command set -x;
    unsilence_autocd;
  elif [[ "$#" == 1 && "$1" == "+x" ]]; then
    silence_autocd;
    command set +x;
  else  
    command set "$@";
  fi;
}

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