[英]bash replace one character from the end of string
I need to replace last dot to character '-' in the string. 我需要将最后一个点替换为字符串中的字符“-”。
# a='2.5.2.pl'
Using the following expression: 使用以下表达式:
# echo ${a/%./-}
I expect to get: 我希望得到:
2.5.2-pl
but i get 但我明白了
2.5.2.pl
I noticed that it doesn't work only if I need to replace the dot from the end to the beginning. 我注意到,仅当我需要从头到尾替换点时,它才起作用。 Why does it happen?
为什么会发生? Of course I can use external programs like awk, sed to solve this problem but I need to solve the problem using only bash.
当然,我可以使用诸如awk,sed之类的外部程序来解决此问题,但我仅需使用bash即可解决问题。
Thanks for advice! 谢谢你的建议!
With bash's Parameter Expansion : 随着bash的参数扩展 :
a='2.5.2.pl'
echo "${a%.*}-${a##*.}"
Output: 输出:
2.5.2-pl
My way is a bit hacky and uses rev
but I tested it and it works! 我的方法有点hacky,使用了
rev
但我对其进行了测试,并且可以正常工作!
echo "$(_b=$(echo "$a" | rev); _b=${_b/./-}; echo "$_b" | rev)"
Basically, I just reversed the character order so the last .
基本上,我只是颠倒了字符顺序,所以最后一个
.
was first and then used ${var/./-}
to replace the dot with a dash and finally reversed the order of the characters again. 首先使用
${var/./-}
,然后使用破折号代替点,最后再次颠倒字符的顺序。
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