如何在bash中的多字符分隔符上分割字符串？

Question

爲什麼不能運行下面的bash代碼？

for i in $(echo "emmbbmmaaddsb" | split -t "mm" ) 
do 
    echo "$i" 
done 

預期輸出：

e 
bb 
aaddsb 

Answer 1

既然你期待換行符，你可以簡單地替換mm所有實例的字符串以換行符。在純天然的bash：

in='emmbbmmaaddsb' 
sep='mm' 
printf '%s\n' "${in//$sep/$'\n'}" 

---

如果你想要做一個較長的輸入流這樣的替換，你可能會更好使用awk，如bash的內置字符串操作不能很好地擴展到超過幾千字節的內容。在​​給出的gsub_literal外殼函數（backending到awk）是適用的：

# Taken from http://mywiki.wooledge.org/BashFAQ/021 

# usage: gsub_literal STR REP 
# replaces all instances of STR with REP. reads from stdin and writes to stdout. 
gsub_literal() { 
    # STR cannot be empty 
    [[ $1 ]] || return 

    # string manip needed to escape '\'s, so awk doesn't expand '\n' and such 
    awk -v str="${1//\\/\\\\}" -v rep="${2//\\/\\\\}" ' 
    # get the length of the search string 
    BEGIN { 
     len = length(str); 
    } 

    { 
     # empty the output string 
     out = ""; 

     # continue looping while the search string is in the line 
     while (i = index($0, str)) { 
     # append everything up to the search string, and the replacement string 
     out = out substr($0, 1, i-1) rep; 

     # remove everything up to and including the first instance of the 
     # search string from the line 
     $0 = substr($0, i + len); 
     } 

     # append whatever is left 
     out = out $0; 

     print out; 
    } 
    ' 
} 

...使用，在這種情況下，如：

gsub_literal "mm" $'\n' <your-input-file.txt >your-output-file.txt 

Answer 2

使用bash：

s="emmbbmmaaddsb" 
for i in "${s//mm/$'\n'}"; do echo "$i"; done 

輸出：

 
e 
bb 
aaddsb 

Answer 3

對於一個正則表達式發生或全局s/regexp/replacement/g，推薦的字符取代工具是sed的命令s/regexp/replacement/，您甚至不需要循環或變量。

管你echo輸出，並嘗試mm替代字符witht換行符\n：

echo "emmbbmmaaddsb" | sed 's/mm/\n/g'

輸出是：

e 
bb 
aaddsb 

Answer 4

更普遍的例子，而無需更換多帶有單個字符分隔符的字符分隔符如下所示：

使用參數擴展：（從@gniourf_gniourf的評論）

#!/bin/bash 

str="LearnABCtoABCSplitABCaABCString" 
delimiter=ABC 
s=$str$delimiter 
array=(); 
while [[ $s ]]; do 
    array+=("${s%%"$delimiter"*}"); 
    s=${s#*"$delimiter"}; 
done; 
declare -p array 

更粗的一種方式

#!/bin/bash 

# main string 
str="LearnABCtoABCSplitABCaABCString" 

# delimiter string 
delimiter="ABC" 

#length of main string 
strLen=${#str} 
#length of delimiter string 
dLen=${#delimiter} 

#iterator for length of string 
i=0 
#length tracker for ongoing substring 
wordLen=0 
#starting position for ongoing substring 
strP=0 

array=() 
while [ $i -lt $strLen ]; do 
    if [ $delimiter == ${str:$i:$dLen} ]; then 
     array+=(${str:strP:$wordLen}) 
     strP=$((i + dLen)) 
     wordLen=0 
     i=$((i + dLen)) 
    fi 
    i=$((i + 1)) 
    wordLen=$((wordLen + 1)) 
done 
array+=(${str:strP:$wordLen}) 

declare -p array 

參考 - Bash Tutorial - Bash Split String