dash 可以代替 bash 作为我的默认 shell 吗？

Question

从我读到的内容来看，dash可以使用以下命令将其制作为 shell

~$ 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的路径/bin/dash。如果我这样做，它不会读取.bashrc但可能正在读取.profile. 这是我的，我.bashrc可以只是剪切和粘贴.bashrc，破折号的行为将与 bash 在历史记录大小、提示类型和我想要或不想要的 cowsay 实例方面完全一样吗？

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

Answer 1

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，那么才是chsh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。

Answer 2

Shell 有两个用途：运行脚本和用于交互式命令行。

Dash 旨在成为一个快速、高效的脚本编写 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。

您可以使破折号成为您的登录外壳。它将读取~/.profile，与其他 Bourne 风格的 shell 相同（除非~/.bash_profile存在特定于 bash 的 shell，否则 bash 会读取它）。DashENV在交互式运行时也会读取，就像大多数现代 Bourne 风格的 shell 一样。¹

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，您的大部分代码都特定于 bash。

推荐背景阅读：Login Shell 和 Non-Login Shell 的区别？

¹_{一些较旧的 Bourne 风格的 shell 在非交互式启动时会读取 ENV，但我认为任何现代版本都不会这样做。Ash 于 2001 年停止这样做。}