Find and replace inside a string variable using sed command - shell scripting

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.

Remove -i option from it, its for inplace editing and you are Good to go, cheers. — RavinderSingh13
– RavinderSingh13, Commented May 20, 2022 at 5:48
Optionally you could: echo $var >> result.log && sed -i "s/OldText/NewText/g" result.log — James Brown
– James Brown, Commented May 20, 2022 at 10:36

ndc85430 · Accepted Answer · 2022-05-20 05:49:52Z

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.

answered May 20, 2022 at 5:49

ndc85430

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Comments

sseLtaH · Accepted Answer · 2022-05-20 05:49:37Z

2

Using sed

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

answered May 20, 2022 at 5:49

sseLtaH

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James Brown · Accepted Answer · 2022-05-20 06:37:03Z

2

If you are using Bash shell, you could:

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

so

$ var=${var/OldText/NewText}

See this for more.

answered May 20, 2022 at 6:23

James Brown

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