Bash PWD 缩短

Question

我正在寻找一个 bash 函数，它可以缩短长路径名，以防止我的 PS1 变量变得过长。类似以下内容的内容

/this/is/the/path/to/a/really/long/directory/i/would/like/shortened

可能最终会变成：

/t../i../t../p../to/a/r../l../d../i/w../like/shortened

采用路径和要缩短的最大可接受字符数的内容对于我的 .bashrc 文件来说是完美的。

Answer 1

没有给出相同的结果，但我的 ~/.bashrc 包含

_PS1 ()
{
    local PRE= NAME="$1" LENGTH="$2";
    [[ "$NAME" != "${NAME#$HOME/}" || -z "${NAME#$HOME}" ]] &&
        PRE+='~' NAME="${NAME#$HOME}" LENGTH=$[LENGTH-1];
    ((${#NAME}>$LENGTH)) && NAME="/...${NAME:$[${#NAME}-LENGTH+4]}";
    echo "$PRE$NAME"
}
PS1='\u@\h:$(_PS1 "$PWD" 20)\$ '

将显示的路径限制为最多 20 个字符。如果路径超过 20 个字符，它将显示为 /...d/like/shortened 或 ~/.../like/shortened。

Answer 2

这是您可能会喜欢的仅 bash 解决方案。这会将路径的每个部分缩短为仍可以通过制表符完成的最短前缀，并使用 * 而不是 .. 作为填充符。

#!/bin/bash

begin="" # The unshortened beginning of the path.
shortbegin="" # The shortened beginning of the path.
current="" # The section of the path we're currently working on.
end="${2:-$(pwd)}/" # The unmodified rest of the path.
end="${end#/}" # Strip the first /
shortenedpath="$end" # The whole path, to check the length.
maxlength="${1:-0}"

shopt -q nullglob && NGV="-s" || NGV="-u" # Store the value for later.
shopt -s nullglob    # Without this, anything that doesn't exist in the filesystem turns into */*/*/...

while [[ "$end" ]] && (( ${#shortenedpath} > maxlength ))
do
  current="${end%%/*}" # everything before the first /
  end="${end#*/}"    # everything after the first /

  shortcur="$current"
  shortcurstar="$current" # No star if we don't shorten it.

  for ((i=${#current}-2; i>=0; i--))
  do
    subcurrent="${current:0:i}"
    matching=("$begin/$subcurrent"*) # Array of all files that start with $subcurrent. 
    (( ${#matching[*]} != 1 )) && break # Stop shortening if more than one file matches.
    shortcur="$subcurrent"
    shortcurstar="$subcurrent*"
  done

  begin="$begin/$current"
  shortbegin="$shortbegin/$shortcurstar"
  shortenedpath="$shortbegin/$end"
done

shortenedpath="${shortenedpath%/}" # strip trailing /
shortenedpath="${shortenedpath#/}" # strip leading /

echo "/$shortenedpath" # Make sure it starts with /

shopt "$NGV" nullglob # Reset nullglob in case this is being used as a function.

将长度作为第一个参数，将路径作为可选的第二个参数。如果没有给出第二个参数，它将使用当前工作目录。

这将尝试缩短到给定的长度以下。如果这是不可能的，它只会给出它可以给出的最短路径。

从算法上来说，这可能很糟糕，但最终速度相当快。 （快速 shell 脚本的关键是避免使用子 shell 和外部命令，尤其是在内部循环中。）

根据设计，它仅缩短 2 个或更多字符（“hom*”与“home”的字符数一样多）。

它并不完美。在某些情况下，它不会尽可能缩短，例如，如果有多个文件名共享前缀的文件（如果 foobar1 和 foobar2 存在，则 foobar3 将不会被缩短。）

Answer 3

仅供参考，Bash 4+ 中有一个内置的 \w “缩短器”：

PROMPT_DIRTRIM=3

将 /var/lib/whatever/foo/bar/baz 缩短为 .../foo/bar/baz。

Answer 4

我对 Evan Krall 的代码做了一些改进。现在，它会检查您的路径是否从 $HOME 开始，并以 ~/ 而不是 /h*/u*/ 开始缩短的变量。

#!/bin/bash

begin="" # The unshortened beginning of the path.
shortbegin="" # The shortened beginning of the path.
current="" # The section of the path we're currently working on.
end="${2:-$(pwd)}/" # The unmodified rest of the path.

if [[ "$end" =~ "$HOME" ]]; then
    INHOME=1
    end="${end#$HOME}" #strip /home/username from start of string
    begin="$HOME"      #start expansion from the right spot
else
    INHOME=0
fi

end="${end#/}" # Strip the first /
shortenedpath="$end" # The whole path, to check the length.
maxlength="${1:-0}"

shopt -q nullglob && NGV="-s" || NGV="-u" # Store the value for later.
shopt -s nullglob    # Without this, anything that doesn't exist in the filesystem turns into */*/*/...

while [[ "$end" ]] && (( ${#shortenedpath} > maxlength ))
do
  current="${end%%/*}" # everything before the first /
  end="${end#*/}"    # everything after the first /

  shortcur="$current"
  shortcurstar="$current" # No star if we don't shorten it.

  for ((i=${#current}-2; i>=0; i--)); do
    subcurrent="${current:0:i}"
    matching=("$begin/$subcurrent"*) # Array of all files that start with $subcurrent. 
    (( ${#matching[*]} != 1 )) && break # Stop shortening if more than one file matches.
    shortcur="$subcurrent"
    shortcurstar="$subcurrent*"
  done

  #advance
  begin="$begin/$current"
  shortbegin="$shortbegin/$shortcurstar"
  shortenedpath="$shortbegin/$end"
done

shortenedpath="${shortenedpath%/}" # strip trailing /
shortenedpath="${shortenedpath#/}" # strip leading /

if [ $INHOME -eq 1 ]; then
  echo "~/$shortenedpath" #make sure it starts with ~/
else
  echo "/$shortenedpath" # Make sure it starts with /
fi

shopt "$NGV" nullglob # Reset nullglob in case this is being used as a function.

另外，这里有一些我放入 .bashrc 文件中的函数，用于缩小 shell 显示的路径。我不确定像这样编辑 $PWD 是否完全安全，因为某些脚本可能依赖于有效的 $PWD 字符串，但到目前为止，我在偶尔使用时还没有遇到问题。请注意，我将上面的脚本保存为“shortdir”并将其放入我的路径中。

function tinypwd(){
    PWD=`shortdir`
}

function hugepwd(){
    PWD=`pwd`
}

编辑 2010 年 10 月 19 日

在 bash 中使用别名的正确方法是修改 $PS1 变量；这就是提示的解析方式。在大多数情况下（99% 的时间），当前路径在提示字符串中为“\w”。我们可以使用 sed 将其替换为 shortdir，如下所示：

#NOTE: trailing space before the closing double-quote (") is a must!!
function tinypwd(){                                                             
    PS1="$(echo $PS1 | sed 's/\\w/\`shortdir\`/g') "
}                                                                               

function hugepwd(){                                                             
    PS1="$(echo $PS1 | sed 's/[`]shortdir[`]/\\w/g') "                            
} 

Answer 5

Python 脚本怎么样？这首先会缩短最长的目录名称，一次一个字符，直到达到其长度目标或无法使路径变得更短。它不会缩短路径中的最后一个目录。

（我开始用普通的 shell 脚本编写这个，但是 bash 在字符串操作方面很糟糕。）

#!/usr/bin/env python
import sys

try:
    path   = sys.argv[1]
    length = int(sys.argv[2])
except:
    print >>sys.stderr, "Usage: $0 <path> <length>"
    sys.exit(1)

while len(path) > length:
    dirs = path.split("/");

    # Find the longest directory in the path.
    max_index  = -1
    max_length = 3

    for i in range(len(dirs) - 1):
        if len(dirs[i]) > max_length:
            max_index  = i
            max_length = len(dirs[i])

    # Shorten it by one character.    
    if max_index >= 0:
        dirs[max_index] = dirs[max_index][:max_length-3] + ".."
        path = "/".join(dirs)

    # Didn't find anything to shorten. This is as good as it gets.
    else:
        break

print path

示例输出：

$ echo $DIR
/this/is/the/path/to/a/really/long/directory/i/would/like/shortened
$ ./shorten.py $DIR 70
/this/is/the/path/to/a/really/long/directory/i/would/like/shortened 
$ ./shorten.py $DIR 65
/this/is/the/path/to/a/really/long/direc../i/would/like/shortened
$ ./shorten.py $DIR 60
/this/is/the/path/to/a/re../long/di../i/would/like/shortened
$ ./shorten.py $DIR 55
/t../is/the/p../to/a/r../l../di../i/wo../like/shortened
$ ./shorten.py $DIR 50
/t../is/the/p../to/a/r../l../d../i/w../l../shortened

Answer 6

这是 Evan 答案的另一种说法：

这个使用加号 (+) 而不是星号 (*) 来表示被截断的路径。它用 ~ 替换 HOME 路径，并完整保留最终目录段。如果最后一段超过 20 个字符，则会将其缩短为制表符补全位并添加省略号 (...)。

#!/bin/bash
# Modified from http://stackoverflow.com/a/1617048/359287
# By Alan Christopher Thomas (http://alanct.com)

__pwd_ps1 ()
{
    begin=""
    homebegin=""
    shortbegin=""
    current=""
    end="${2:-$(pwd)}/" # The unmodified rest of the path.
    end="${end#/}" # Strip the first /
    shortenedpath="$end"

    shopt -q nullglob && NGV="-s" || NGV="-u"
    shopt -s nullglob

    while [[ "$end" ]]
    do
      current="${end%%/*}" # Everything before the first /
      end="${end#*/}" # Everything after the first /

      shortcur="$current"
      for ((i=${#current}-2; i>=0; i--))
      do
        [[ ${#current} -le 20 ]] && [[ -z "$end" ]] && break
        subcurrent="${current:0:i}"
        matching=("$begin/$subcurrent"*) # Array of all files that start with $subcurrent
        (( ${#matching[*]} != 1 )) && break # Stop shortening if more than one file matches
        [[ -z "$end" ]] && shortcur="$subcurrent..." # Add character filler at the end of this string
        [[ -n "$end" ]] && shortcur="$subcurrent+" # Add character filler at the end of this string
      done

      begin="$begin/$current"
      homebegin="$homebegin/$current"
      [[ "$homebegin" =~ ^"$HOME"(/|$) ]] && homebegin="~${homebegin#$HOME}" # Convert HOME to ~
      shortbegin="$shortbegin/$shortcur"
      [[ "$homebegin" == "~" ]] && shortbegin="~" # Use ~ for home
      shortenedpath="$shortbegin/$end"
    done

    shortenedpath="${shortenedpath%/}" # Strip trailing /
    shortenedpath="${shortenedpath#/}" # Strip leading /

    [[ ! "$shortenedpath" =~ ^"~" ]] && printf "/$shortenedpath" # Make sure it starts with /
    [[ "$shortenedpath" =~ ^"~" ]] && printf "$shortenedpath" # Don't use / for home dir

    shopt "$NGV" nullglob # Reset nullglob in case this is being used as a function.
}

在此处下载脚本并将其包含在您的 .bashrc 中：

https://raw.github.com/alanctkc/dotfiles/master/.bash_scripts/pwd-prompt.bash

. ~/.bash_scripts/pwd-prompt.bash

将目录添加到您的 PS1 中，如下所示：

export PS1="[other stuff...] \$(__pwd_ps1)\$ "

Answer 7

这是一个相对简单的 Perl 解决方案。这很短
足以让你可以直接将其嵌入到 PS1 中
而不是调用脚本。它给出了所有的字符
截断的名称而不是替换为“.”

$ echo '/this/is/a/realy/long/path/id/like/shortened' |
 perl -F/ -ane 'print join( "/", map { $i++ < @F - 2 ?
 substr $_,0,3 : $_ } @F)'
/thi/is/a/rea/lon/pat/id/like/shortened

我没有立即找到用“.”替换字符的好方法，
但这是一个丑陋的方法：

echo '/this/is/a/realy/long/path/id/like/shortened' |
 perl -F/ -ane 'print join( "/", map { m/(.)(.*)/;
 $_ = $1 . "." x (length $2 > 2 ? 2 : length $2 ) if $i++ < @F - 2; $_ } @F)'
/t../i./a/r../l../p../i./like/shortened

Answer 8

试试这个：

PS1='$(pp="$PWD/" q=${pp/#"$HOME/"/} p=${q%?};((${#p}>19))&&echo "${p::9}…${p:(-9)}"||echo "$p") \
它转换
~/.vim/bundle/ack.vim/plugin

为
.vim/bund…im/plugin

transfrom
/usr/share/doc/xorg-x11-font-utils-7.5/

 to
/usr/shar…utils-7.5

当 $PWD 与 $HOME 相同时，不显示任何内容。
奖励：您可以修改长度数量以满足您的需要。

它转换

为

transfrom

to

当 $PWD 与 $HOME 相同时，不显示任何内容。

奖励：您可以修改长度数量以满足您的需要。