bash 使用 shell 脚本剪切字符串中的最后 n 个字符
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cutting last n character in a string using shell script
提问by anish
How to remove all n characters from a particular string using shell scripts,
如何使用 shell 脚本从特定字符串中删除所有 n 个字符，
ssl01:49188,,,
ssl01:49188,
ssl01:49188,,,,,
ssl01:49188,ssl999999:49188,,,,,
ssl01:49188,abcf999:49188,,,,,
The output will be in the following format
输出将采用以下格式
ssl01:49188
ssl01:49188
ssl01:49188
ssl01:49188,ssl999999:49188
ssl01:49188,abcf999:49188
回答by Shawn Chin
To answer the title of you question with specifies cutting last n character in a string, you can use the substring extraction feature in Bash.
要通过指定剪切字符串中的最后 n 个字符来回答问题的标题，您可以使用 Bash 中的子字符串提取功能。
me@home$ A="123456"
me@home$ echo ${A:0:-2} # remove last 2 chars
1234
However, based on your examples you appear to want to remove all trailing commas, in which case you could use sed 's/,*$//'.
但是，根据您的示例，您似乎想要删除所有尾随逗号，在这种情况下，您可以使用sed 's/,*$//'.
me@home$ echo "ssl01:49188,ssl999999:49188,,,,," | sed 's/,*$//'
ssl01:49188,ssl999999:49188
or, for a purely Bash solution, you could use substring removal:
或者，对于纯粹的 Bash 解决方案，您可以使用子字符串删除：
me@home$ X="ssl01:49188,ssl999999:49188,,,,,"
me@home$ shopt -s extglob
me@home$ echo ${X%%+(,)}
ssl01:49188,ssl999999:49188
I would use the sedapproach if the transformation needs to be applied to a whole file, and the bash substring removal approach if the target string is already in a bash variable.
sed如果需要将转换应用于整个文件，我会使用这种方法，如果目标字符串已经在 bash 变量中，我会使用bash 子字符串删除方法。
回答by cmbuckley
With sed:
与sed：
sed 's/,\+$//' file
回答by Vijay
I guess you need to remove those unnecessary ,'s
我想你需要删除那些不必要,的
sed 's/,,//g;s/\,$//g' your_file
tested:
测试：
> cat temp
ssl01:49188,,,
ssl01:49188,
ssl01:49188,,,,,
ssl01:49188,,,
ssl01:49188,
ssl01:49188,,,,,
ssl01:49188,ssl999999:49188,,,,,
ssl01:49188,abcf999:49188,,,,,
> sed 's/,,//g;s/\,$//g' temp
ssl01:49188
ssl01:49188
ssl01:49188
ssl01:49188
ssl01:49188
ssl01:49188
ssl01:49188,ssl999999:49188
ssl01:49188,abcf999:49188
>
回答by Guru
Using sed:
使用 sed：
sed 's/,,*$//g' file
