How to delete a string from a file in bash

Question

I want to delete a string from a file. This string is provided by the user. I tried the following command which didn’t work.

read -r input
sed -i '/"$input"/d' xyz.txt

I tried without double quotes("") as well. But it didn’t work.

Could you guys please help me?

You said you want to delete a string, but the command you've used deletes the whole line the string is in. This is a different outcome than what you've expressed. Which is desired? — SaintHax
– SaintHax, Commented Apr 4, 2016 at 12:53

anubhava · Accepted Answer · 2016-04-04 11:42:57Z

3

You can use:

sed -i "/$input/d" xyz.txt

but make sure input doesn't contain any regex special character.

awk with index function might be safer due to non-regex:

awk -v input="$input" '!index($0, input)' xyz.txt > $$.temp && mv $$.temp xyz.txt

answered Apr 4, 2016 at 11:42

anubhava

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Comments

heemayl · Accepted Answer · 2016-04-04 11:46:51Z

1

The problem is that variables won't be expanded when put inside single quotes.

So you need to use double quotes:

sed -i.bak "/$input/ d" xyz.txt

The original file will be kept as xyz.txt.bak and the modified file will be xyz.txt.

If you do not want a backup:

sed -i "/$input/ d" xyz.txt

answered Apr 4, 2016 at 11:46

heemayl

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