在bash中将字符串拆分为数组 [英] Split string into array in bash

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本文介绍了在bash中将字符串拆分为数组的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我正在寻找一种方法，可以将bash中的字符串分割成定界符字符串，并将其放置在数组中.

I am looking for a way to split a string in bash over a delimiter string, and place the parts in an array.

简单情况:

#!/bin/bash
b="aaaaa/bbbbb/ddd/ffffff"
echo "simple string: $b"

IFS='/' b_split=($b)
echo ;
echo "split"
for i in ${b_split[@]}
do
    echo "------ new part ------"
    echo "$i"
done

提供输出

simple string: aaaaa/bbbbb/ddd/ffffff

split
------ new part ------
aaaaa
------ new part ------
bbbbb
------ new part ------
ddd
------ new part ------
ffffff

更复杂的情况:

#!/bin/bash
c=$(echo "AA=A"; echo "B=BB"; echo "======="; echo "C==CC"; echo "DD=D"; echo "======="; echo "EEE"; echo "FF";)
echo "more complex string"
echo "$c";
echo ;
echo "split";

IFS='=======' c_split=($c) ;#    <----    LINE TO BE CHANGED 

for i in ${c_split[@]}
do
    echo "------ new part ------"
    echo "$i"
done

给出输出:

more complex string
AA=A
B=BB
=======
C==CC
DD=D
=======
EEE
FF

split
------ new part ------
AA
------ new part ------
A
B
------ new part ------
BB

------ new part ------

------ new part ------

------ new part ------

------ new part ------

------ new part ------

------ new part ------

------ new part ------

C
------ new part ------

------ new part ------
CC
DD
------ new part ------
D

------ new part ------

------ new part ------

------ new part ------

------ new part ------

------ new part ------

------ new part ------

------ new part ------

EEE
FF

我希望第二个输出像

------ new part ------
AA=A
B=BB
------ new part ------
C==CC
DD=D
------ new part ------
EEE
FF

即将字符串分割成一个字符顺序，而不是一个.我该怎么办?

I.e. to split the string on a sequence of characters, instead of one. How can I do this?

我正在寻找仅会在第二个脚本中修改此行的答案:

I am looking for an answer that would only modify this line in the second script:

IFS='=======' c_split=($c) ;#    <----    LINE TO BE CHANGED

推荐答案

IFS消除歧义

IFS表示输入字段分隔符，为 list of characters that could be used as separators .

IFS disambiguation

IFS mean Input Field Separators, as list of characters that could be used as separators.

默认情况下，此设置为 \t\n，表示空格，制表 和/或任何数量(大于零) 换行符可以是一个 separator .

By default, this is set to \t\n, meaning that any number (greater than zero) of space, tabulation and/or newline could be one separator.

所以字符串:

 "    blah  foo=bar 
 baz  "

前导和尾随分隔符将被忽略，该字符串仅包含3个 部分:blah，foo=bar和baz.

Leading and trailing separators would be ignored and this string will contain only 3 parts: blah, foo=bar and baz.

如果您知道在字符串中未使用有效的字段分隔符，则可以使用IFS分隔字符串.

Splitting a string using IFS is possible if you know a valid field separator not used in your string.

OIFS="$IFS"
IFS='§'
c=$'AA=A\nB=BB\n=======\nC==CC\nDD=D\n=======\nEEE\nFF'
c_split=(${c//=======/§})
IFS="$OIFS"
printf -- "------ new part ------\n%s\n" "${c_split[@]}"

------ new part ------
AA=A
B=BB

------ new part ------

C==CC
DD=D

------ new part ------

EEE
FF

但这仅在字符串不包含§时起作用.

But this work only while string do not contain §.

您可以使用其他字符，例如IFS=$'\026';c_split=(${c//=======/$'\026'})，但是无论如何，这可能会涉及到臭虫.

You could use another character, like IFS=$'\026';c_split=(${c//=======/$'\026'}) but anyway this may involve furter bugs.

您可以浏览字符映射表以查找不在您的字符串中的人:

You could browse character maps for finding one who's not in your string:

myIfs=""
for i in {1..255};do
    printf -v char "$(printf "\\\%03o" $i)"
        [ "$c" == "${c#*$char}" ] && myIfs="$char" && break
  done
if ! [ "$myIFS" ] ;then
    echo no split char found, could not do the job, sorry.
    exit 1
  fi

但我发现此解决方案有些过分.

but I find this solution a little overkill.

在的问题下，我们可以使用这种bashism :

Under bash, we could use this bashism:

b="aaaaa/bbbbb/ddd/ffffff"
b_split=(${b//// })

实际上，此语法${varname//将启动转换(用/分隔)，将所有/出现的位置替换为空格，之前，将其分配给数组b_split.

In fact, this syntaxe ${varname// will initiate a translation (delimited by /) replacing all occurences of / by a space , before assigning it to an array b_split.

当然，它仍然使用IFS并在空格上分割数组.

Of course, this still use IFS and split array on spaces.

这不是最好的方法，但是可以处理特定的情况.

This is not the best way, but could work with specific cases.

您甚至可以在拆分之前丢下多余的空格:

You could even drop unwanted spaces before splitting:

b='12 34 / 1 3 5 7 / ab'
b1=${b// }
b_split=(${b1//// })
printf "<%s>, " "${b_split[@]}" ;echo
<12>, <34>, <1>, <3>, <5>, <7>, <ab>,

或交换他们... 

b1=${b// /§}
b_split=(${b1//// })
printf "<%s>, " "${b_split[@]//§/ }" ;echo
<12 34 >, < 1 3 5 7 >, < ab>,

strings 上的分割线:

因此，您不必不要使用IFS来表示您的意思，但

Splitting line on strings:

So you have to not use IFS for your meaning, but bash do have nice features:

#!/bin/bash

c=$'AA=A\nB=BB\n=======\nC==CC\nDD=D\n=======\nEEE\nFF'
echo "more complex string"
echo "$c";
echo ;
echo "split";

mySep='======='
while [ "$c" != "${c#*$mySep}" ];do
    echo "------ new part ------"
    echo "${c%%$mySep*}"
    c="${c#*$mySep}"
  done
echo "------ last part ------"
echo "$c"

让我们看看:

more complex string
AA=A
B=BB
=======
C==CC
DD=D
=======
EEE
FF

split
------ new part ------
AA=A
B=BB

------ new part ------

C==CC
DD=D

------ last part ------

EEE
FF

注意:不删除开头和结尾的换行符.如果需要，您可以:

Nota: Leading and trailing newlines are not deleted. If this is needed, you could:

mySep=$'\n=======\n'

而不是简单的=======.

或者您可以重写split循环以明确地将其排除在外:

Or you could rewrite split loop for keeping explicitely this out:

mySep=$'======='
while [ "$c" != "${c#*$mySep}" ];do
    echo "------ new part ------"
    part="${c%%$mySep*}"
    part="${part##$'\n'}"
    echo "${part%%$'\n'}"
    c="${c#*$mySep}"
  done
echo "------ last part ------"
c=${c##$'\n'}
echo "${c%%$'\n'}"

任何情况下，这都符合SO问题所要求的(:和他的样本:)

Any case, this match what SO question asked for (: and his sample :)

------ new part ------
AA=A
B=BB
------ new part ------
C==CC
DD=D
------ last part ------
EEE
FF

最后创建一个 array 

#!/bin/bash
c=$'AA=A\nB=BB\n=======\nC==CC\nDD=D\n=======\nEEE\nFF'
echo "more complex string"
echo "$c";
echo ;
echo "split";

mySep=$'======='
export -a c_split
while [ "$c" != "${c#*$mySep}" ];do
    part="${c%%$mySep*}"
    part="${part##$'\n'}"
    c_split+=("${part%%$'\n'}")
    c="${c#*$mySep}"
  done
c=${c##$'\n'}
c_split+=("${c%%$'\n'}")

for i in "${c_split[@]}"
do
    echo "------ new part ------"
    echo "$i"
done

很好地做到这一点:

more complex string
AA=A
B=BB
=======
C==CC
DD=D
=======
EEE
FF

split
------ new part ------
AA=A
B=BB
------ new part ------
C==CC
DD=D
------ new part ------
EEE
FF

一些解释:

  • export -a var将var定义为数组并在子级中共享它们
  • ${variablename%string*}，${variablename%%string*}导致变量名的左侧，直到但没有 string .一个%表示最后一次出现字符串，而%%表示所有出现.如果找不到 string ，则会返回完整的 variablename .
  • ${variablename#*string}，以相反的方式进行操作:从中返回变量名的最后一部分，但不包含 string .一个#平均首次出现和两个##男性全部出现.

    • Some explanations:

    • export -a var to define var as an array and share them in childs
    • ${variablename%string*}, ${variablename%%string*} result in the left part of variablename, upto but without string. One % mean last occurence of string and %% for all occurences. Full variablename is returned is string not found.
    • ${variablename#*string}, do same in reverse way: return last part of variablename from but without string. One # mean first occurence and two ## man all occurences.

      • Nota替换中，字符*是小丑，表示任意数量的任何字符.

      Nota in replacement, character * is a joker mean any number of any character.

      命令echo "${c%%$'\n'}"将回显变量 c ，但字符串末尾没有任何换行符.

      The command echo "${c%%$'\n'}" would echo variable c but without any number of newline at end of string.

      因此，如果变量包含Hello WorldZorGluBHello youZorGluBI'm happy，

      variable="Hello WorldZorGluBHello youZorGluBI'm happy"

$ echo ${variable#*ZorGluB}
Hello youZorGlubI'm happy

$ echo ${variable##*ZorGluB}
I'm happy

$ echo ${variable%ZorGluB*}
Hello WorldZorGluBHello you

$ echo ${variable%%ZorGluB*}
Hello World

$ echo ${variable%%ZorGluB}
Hello WorldZorGluBHello youZorGluBI'm happy

$ echo ${variable%happy}
Hello WorldZorGluBHello youZorGluBI'm

$ echo ${variable##* }
happy

      所有这些内容都在联机帮助页中进行了说明:

      All this is explained in the manpage:

      $ man -Len -Pless\ +/##word bash

$ man -Len -Pless\ +/%%word bash

$ man -Len -Pless\ +/^\\\ *export\\\ .*word bash

      分步循环:

      分隔符:

      Step by step, the splitting loop:

      The separator:

      mySep=$'======='

      将c_split声明为 array (可以与孩子共享)

      Declaring c_split as an array (and could be shared with childs)

      export -a c_split

      变量 c 确实包含至少一个mySep

      While variable c do contain at least one occurence of mySep

      while [ "$c" != "${c#*$mySep}" ];do

      从第一个mySep到字符串的结尾

      截断 c 并分配给part.

      Trunc c from first mySep to end of string and assign to part.

          part="${c%%$mySep*}"

      删除主要的换行符

          part="${part##$'\n'}"

      删除尾随的换行符，并将结果作为新的数组元素添加到c_split.

      Remove trailing newlines and add result as a new array element to c_split.

          c_split+=("${part%%$'\n'}")

      重置 c ，直到剩下的mySep都删除了字符串的其余部分

      Reassing c whith the rest of string when left upto mySep is removed

          c="${c#*$mySep}"

      完成;-)

      done

      删除主要的换行符

      c=${c##$'\n'}

      删除尾随的换行符，并将结果作为新的数组元素添加到c_split.

      Remove trailing newlines and add result as a new array element to c_split.

      c_split+=("${c%%$'\n'}")

      进入功能:

      ssplit() {
    local string="$1" array=${2:-ssplited_array} delim="${3:- }" pos=0
    while [ "$string" != "${string#*$delim}" ];do
        printf -v $array[pos++] "%s" "${string%%$delim*}"
        string="${string#*$delim}"
      done
    printf -v $array[pos] "%s" "$string"
}

      用法:

      ssplit "<quoted string>" [array name] [delimiter string]

      其中数组名称默认为$splitted_array，分隔符为单个空格.

      where array name is $splitted_array by default and delimiter is one single space.

      您可以使用:

      c=$'AA=A\nB=BB\n=======\nC==CC\nDD=D\n=======\nEEE\nFF'
ssplit "$c" c_split $'\n=======\n'
printf -- "--- part ----\n%s\n" "${c_split[@]}"
--- part ----
AA=A
B=BB
--- part ----
C==CC
DD=D
--- part ----
EEE
FF

      这篇关于在bash中将字符串拆分为数组的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！

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