Replace a string using sed

Question

I want to replace a string ip_ttl="1" with ip_ttl="2" using sed.

I've tried sed -i "s/ip_ttl="1"/ip_ttl="2"/g" - but its not working.

Please help!

If you do that you are opening and closing the thing twice. You have to use a different type of quotation marks — user4396006
– user4396006, Commented Mar 27, 2015 at 6:54
@mins This question could be here since it is coding (source of code) problem not simply a unix problem (even if the real problem is a shell interpretation in this case, know from the OP only when solution is provided) — NeronLeVelu
– NeronLeVelu, Commented Mar 27, 2015 at 13:48

Avinash Raj · Accepted Answer · 2015-03-27 06:59:07Z

2

Put your sed code inside single quotes, because your code already contains double quotes.

sed -i 's/ip_ttl="1"/ip_ttl="2"/g' file

If you put your code within two double quotes, sed would terminate the program once another double quote was reached. So " before 1 was reached, it would consider as the end and terminates the program.

Update:

If the number always changes then it's better to define the pattern which matches any number.

sed -i 's/ip_ttl="[0-9]\+"/ip_ttl="2"/g' file

edited Mar 27, 2015 at 6:59

answered Mar 27, 2015 at 6:50

Avinash Raj

175k32 gold badges247 silver badges289 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Ravikanth Over a year ago

one more thing ip_ttl="1" will get changed from 1 to 0 or any number - should replace with ip_ttl="2"

baf · Accepted Answer · 2015-03-27 06:56:40Z

1

If you are using quotation marks in your pattern either escape double quotes in pattern:

sed -i "s/ip_ttl=\"1\"/ip_ttl=\"2\"/g"

or enclose whole pattern in single quotes:

sed -i 's/ip_ttl="1"/ip_ttl="2"/g'

answered Mar 27, 2015 at 6:56

baf

4,7211 gold badge23 silver badges25 bronze badges

2 Comments

Ravikanth Over a year ago

we have one more problem - trying to replace timeToLive=99(dynamic value it it) with timeToLive=0 from the file , the format sed -i 's/timeToLive=*/timeToLive=0/g' is not replacing properly, please suggest

baf Over a year ago

sed -i 's/timeToLive=[0-9]\+/timeToLive=0/g'

jcuenod · Accepted Answer · 2015-03-27 06:53:46Z

0

Alternatively you can escape the quotation marks

sed -i "s/ip_ttl=\"1\"/ip_ttl=\"2\"/g" file

Sometimes that's useful because you have both single and double quotes in a string you're selecting for.

answered Mar 27, 2015 at 6:53

jcuenod

58.9k15 gold badges71 silver badges103 bronze badges

1 Comment

jcuenod Over a year ago

Welcome to regex. I did say "alternatively" because I agree, it does make it complex but you can't escape escaping.

Collectives™ on Stack Overflow

Replace a string using sed

3 Answers 3

1 Comment

2 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

2 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related