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dash 可以取代 bash 作为我的默认 shell 吗？

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dash 可以取代 bash 作为我的默认 shell 吗？

据我所知，dash可以使用命令将其制作为外壳

~$ chsh shirish
Password: 
Changing the login shell for shirish
Enter the new value, or press ENTER for the default
    Login Shell [/bin/bash]:

我只需要安装 dash 并给出登录 shell /bin/dash 的路径。如果我这样做，它不会读取.bashrc，但可能正在读取.profile。这是我的.bashrc，我可以直接剪切和粘贴吗？.bashrc破折号的行为与 bash 的行为完全一样，参考历史记录大小、提示类型和我想要的cowsay 实例吗？

这是我的.bashrc。

$ cat .bashrc
# ~/.bashrc: executed by bash(1) for non-login shells.
# see /usr/share/doc/bash/examples/startup-files (in the package bash-doc)
# for examples

# If not running interactively, don't do anything
case $- in
    *i*) ;;
      *) return;;
esac

# don't put duplicate lines or lines starting with space in the history.
# See bash(1) for more options
HISTCONTROL=ignoreboth

# append to the history file, don't overwrite it
shopt -s histappend

# for setting history length see HISTSIZE and HISTFILESIZE in bash(1)
HISTSIZE=3000
HISTFILESIZE=3000
HISTTIMEFORMAT="%F %T"

# check the window size after each command and, if necessary,
# update the values of LINES and COLUMNS.
shopt -s checkwinsize

# If set, the pattern "**" used in a pathname expansion context will
# match all files and zero or more directories and subdirectories.
#shopt -s globstar

# make less more friendly for non-text input files, see lesspipe(1)
#[ -x /usr/bin/lesspipe ] && eval "$(SHELL=/bin/sh lesspipe)"

# set variable identifying the chroot you work in (used in the prompt below)
if [ -z "${debian_chroot:-}" ] && [ -r /etc/debian_chroot ]; then
    debian_chroot=$(cat /etc/debian_chroot)
fi

# set a fancy prompt (non-color, unless we know we "want" color)
case "$TERM" in
    xterm-color) color_prompt=yes;;
esac

# uncomment for a colored prompt, if the terminal has the capability; turned
# off by default to not distract the user: the focus in a terminal window
# should be on the output of commands, not on the prompt
#force_color_prompt=yes

if [ -n "$force_color_prompt" ]; then
    if [ -x /usr/bin/tput ] && tput setaf 1 >&/dev/null; then
    # We have color support; assume it's compliant with Ecma-48
    # (ISO/IEC-6429). (Lack of such support is extremely rare, and such
    # a case would tend to support setf rather than setaf.)
    color_prompt=yes
    else
    color_prompt=
    fi
fi

# enable bash completion in interactive shells
if ! shopt -oq posix; then
  if [ -f /usr/share/bash-completion/bash_completion ]; then
    . /usr/share/bash-completion/bash_completion
  elif [ -f /etc/bash_completion ]; then
    . /etc/bash_completion
  fi
fi

if [ "$color_prompt" = yes ]; then
    PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ '
else
    PS1='${debian_chroot:+($debian_chroot)}\t \u@\h:\w\$ '
fi
unset color_prompt force_color_prompt

# If this is an xterm set the title to user@host:dir
case "$TERM" in
xterm*|rxvt*)
    PS1="\[\e]0;${debian_chroot:+($debian_chroot)}\u@\h: \w\a\]$PS1"
    ;;
*)
    ;;
esac

# enable color support of ls and also add handy aliases
if [ -x /usr/bin/dircolors ]; then
    test -r ~/.dircolors && eval "$(dircolors -b ~/.dircolors)" || eval "$(dircolors -b)"
    alias    ls='ls --color=auto'
    alias   cls='clear'
    alias    ll='ls -l'
    alias aptfn='sudo aptitude forget-new'
    alias  aptn="aptitude search '~N'"
    alias    gi='bash /home/shirish/git-info.sh'
    alias  apto='aptitude search ~o'
    alias  grep='grep --color=auto'
    alias  aptc="aptitude search '~c'"
    alias  copy="rsync --progress -ravz"
    alias   vlc="vlc -vv"
    alias   tor="/home/shirish/.local/share/torbrowser/tbb/x86_64/tor-browser_en-US/start-tor-browser"

    #alias dir='dir --color=auto'
    #alias vdir='vdir --color=auto'
    #alias grep='grep --color=auto'
    #alias fgrep='fgrep --color=auto'
    #alias egrep='egrep --color=auto'
fi

# some more ls aliases

#alias la='ls -A'
#alias l='ls -CF'

# Alias definitions.
# You may want to put all your additions into a separate file like
# ~/.bash_aliases, instead of adding them here directly.
# See /usr/share/doc/bash-doc/examples in the bash-doc package.

#if [ -f ~/.bash_aliases ]; then
#    . ~/.bash_aliases
#fi

# from http://askubuntu.com/questions/16428/showing-a-cowsay-fortune-in-every-new-terminal-session

if [ -x /usr/games/cowsay -a -x /usr/games/fortune ]; then
    fortune | cowsay

答案1

Shell 有两种用途：运行脚本和交互式命令行。

Dash 被设计为一个快速、高效的脚本 shell。它几乎没有交互式使用的好功能。它没有花哨的提示、命令行编辑功能或命令历史记录。

您可以将 dash 作为登录 shell。它将读取~/.profile，与其他 Bourne 风格的 shell 相同（除非 bash 特定的~/.bash_profile存在，否则 bash 读取它）。 Dash 也会ENV在交互运行时读取数据，就像大多数现代 Bourne 风格的 shell 一样。

对于交互式使用，请使用功能更强大的 shell：fish、zsh 或 bash。.bashrc除了可以在其他 shell 中工作的别名定义之外，您中的大部分代码都是特定于 bash 的。

推荐背景阅读：登录 Shell 和非登录 Shell 之间的区别？

一些较旧的 Bourne 风格的 shell 在以非交互方式启动时会读取 ENV，但我认为任何现代版本都不会这样做。 Ash 在 2001 年停止了这样做。

答案2

您中的许多命令.bashrc都是bash特定的。诸如此类的事情HISTCONTROL与 无关dash。命令完成也是如此。不过，别名可以使用。

阅读 的联机帮助页dash并检查您在 中所做的每件事的联机帮助页，.bashrc看看它是否适用于dash.

您问的真正问题不是很清楚：您只是想dash安装为/bin/sh，还是您真的希望 dash 作为您的登录 shell？如果是后者，那么chsh才是正确的做法；否则，您只需要安装dash，安装程序将询问您是否希望 dash 成为默认系统 shell（然后选择“是”）。如果您想更改答案，请运行dpkg-reconfigure dash。

答案3

您可以轻松地亲自尝试一下，看看它们是否有效，而无需更改当前的登录 shell。

除了/etc/profile和之外~/.profile，将以交互方式启动时dash读取环境变量指向的文件，如下所示：ENV

ENV=~/.bashrc dash

或者更好地复制您的~/.bashrcto~/.dashrc并注释掉/删除您不需要/不起作用的内容。一旦你拥有了你喜欢的一切，你就可以添加一行

ENV=~/.dashrc

到你的~/.profile并更改你的默认外壳。

从man dash：

 ...   If the environment variable ENV is set on entry to an interac‐
 tive shell, or is set in the .profile of a login shell, the shell next
 reads commands from the file named in ENV.  Therefore, a user should
 place commands that are to be executed only at login time in the
 .profile file, and commands that are executed for every interactive
 shell inside the ENV file.  To set the ENV variable to some file, place
 the following line in your .profile of your home directory

       ENV=$HOME/.shinit; export ENV

 substituting for “.shinit” any filename you wish.

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