使用 sed 命令在字符串变量中查找和替换 - shell 脚本

Question

lets say I have a string variable variable

var="This line is with OldText"

I want to find and replace the text inside this variable The method that I tried is,

echo $var | sed -i "s/OldText/NewText/g"  >> result.log

in this case this gives an error saying "no input files". The expected output is ,

"This line is with NewText"

what is the correct method to do this using sed, awk or any other method.

Answer 1

Using sed

$ var=$(sed "s/OldText/NewText/" <<< $var)
$ echo $var
This line is with NewText

Answer 2

You don't use -i , as that's for changing a file in place. If you want to replace the value in the variable, you need to reassign to it.

Answer 3

If you are using Bash shell, you could:

$ echo ${var/OldText/NewText}
This line is with NewText

so

$ var=${var/OldText/NewText}

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