LinuxQuestions.org - [SOLVED] Use sed to replace a single letter?

- Linux - Newbie (https://www.linuxquestions.org/questions/linux-newbie-8/)

- - Use sed to replace a single letter? (https://www.linuxquestions.org/questions/linux-newbie-8/use-sed-to-replace-a-single-letter-4175486459/)

Spazztic_Killer

12-01-2013 11:59 AM

Use sed to replace a single letter?

I cant seem to get sed to replace a single letter, when i use

Code:

sed -e 's/J/M/g'

It ends up matching more than a single letter of the data and replaces it to.

The data looks like

lastname:firstname:middlename

Quote:

Smith:James:J

it will look like

Quote:

Smith:Mames:M

Not sure how to confine sed to a single letter match?

druuna

12-01-2013 12:18 PM

The g makes it global (for all instances in the line). If you remove the g then only the first instance will be changed:

Code:

sed 's/J/M/'

You can change the second occurrence like this:

Code:

sed 's/J/M/2'

If the letter is the last on a line:

Code:

sed 's/J$/M/'

- Sed - An Introduction and Tutorial
- sed, a stream editor

Shadow_7

12-01-2013 12:46 PM

^ as above. The /g makes it do it multiple times for every instance in a line. Drop the g and it does the first instance only.

Madhu Desai

12-01-2013 11:45 PM

Quote:

Originally Posted by Spazztic_Killer (Post 5073460)

Not sure how to confine sed to a single letter match?

You can use word boundary (\< \> ot \b) to achieve it.

Code:

sed 's/\<J\>/M/g'

sed 's/\bJ\b/M/g'

All times are GMT -5. The time now is 10:04 AM.