如何在由制表符分隔的 bash 中拆分字符串
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How to split a string in bash delimited by tab
提问by chaimp
I'm trying to split a tab delimitted field in bash.
我正在尝试在 bash 中拆分制表符分隔的字段。
I am aware of this answer: how to split a string in shell and get the last field
我知道这个答案：how to split a string in shell and get the last field
But that does not answer for a tab character.
但这并不能回答制表符。
I want to do get the part of a string before the tab character, so I'm doing this:
我想在制表符之前获取字符串的一部分，所以我这样做：
x=`head -1 my-file.txt`
echo ${x%\t*}
But the \t is matching on the letter 't' and not on a tab. What is the best way to do this?
但是 \t 匹配字母 't' 而不是选项卡。做这个的最好方式是什么？
Thanks
谢谢
回答by Fredrik Pihl
If your file look something like this (with tab as separator):
如果您的文件看起来像这样（使用制表符作为分隔符）：
1st-field 2nd-field
you can use cutto extract the first field (operates on tab by default):
您可以cut用来提取第一个字段（默认在选项卡上操作）：
$ cut -f1 input
1st-field
If you're using awk, there is no need to use tailto get the last line, changing the input to:
如果您正在使用awk，则无需使用tail获取最后一行，将输入更改为：
1:1st-field 2nd-field
2:1st-field 2nd-field
3:1st-field 2nd-field
4:1st-field 2nd-field
5:1st-field 2nd-field
6:1st-field 2nd-field
7:1st-field 2nd-field
8:1st-field 2nd-field
9:1st-field 2nd-field
10:1st-field 2nd-field
Solution using awk:
使用awk的解决方法：
$ awk 'END {print }' input
10:1st-field
Pure bash-solution:
纯 bash 解决方案：
#!/bin/bash
while read a b;do last=$a; done < input
echo $last
outputs:
输出：
$ ./tab.sh
10:1st-field
Lastly, a solution using sed
最后，解决方案使用 sed
$ sed '$s/\(^[^\t]*\).*$//' input
10:1st-field
here, $is the range operator; i.e. operate on the last line only.
这里，$是范围运算符；即只在最后一行操作。
For your original question, use a literal tab, i.e.
对于您的原始问题，请使用文字选项卡，即
x="1st-field 2nd-field"
echo ${x% *}
outputs:
输出：
1st-field
回答by glenn Hymanman
Use $'ANSI-C'stringsin the parameter expansion:
在参数扩展中使用$'ANSI-C'字符串：
$ x=$'abc\tdef\tghi'
$ echo "$s"
abc def ghi
$ echo ">>${x%%$'\t'*}<<"
>>abc<<
回答by Michael
Use awk.
使用awk。
echo $yourfield | awk '{print }'
or, in your case, for the first field from the the last line of a file
或者，在您的情况下，对于文件最后一行的第一个字段
tail yourfile | awk '{x=}END{print x}'
回答by user9118869
read field1 field2 <<< ${tabDelimitedField}
or
或者
read field1 field2 <<< $(command_producing_tab_delimited_output)
回答by Denis Capart
There is an easy way for a tab separated string : convert it to an array.
制表符分隔的字符串有一种简单的方法：将其转换为数组。
Create a string with tabs ($ added before for '\t' interpretation) :
创建一个带有制表符的字符串（在 '\t' 解释之前添加了 $）：
AAA=$'ABC\tDEF\tGHI'
Split the string as an array using parenthesis :
使用括号将字符串拆分为数组：
BBB=($AAA)
Get access to any element :
访问任何元素：
echo ${BBB[0]}
ABC
echo ${BBB[1]}
DEF
echo ${BBB[2]}
GHI
回答by Luchostein
x=first$'\t'second
echo "${x%$'\t'*}"
See QUOTINGin man bash
见QUOTING在man bash
