CODEWITHSUNDEEP
bashsedgrep
peachy
peachy

Reputation: 11

Why is this grep + sed pipeline not doing what I thought it would do?

I'm using this command here of grep and sed,

grep -w 'HN8 .* ATP' topol.top | sed -i 's_0[.]09_0.054_' topol.top

In my head, I thought the command is fetch lines that have HN8 and ATP, in those lines, replace 0.09 with 0.054. However, when this happens, Lines with HN7 or HN6 etc, with 0.09 are also getting swapped to 0.054.

Whys that? so I can understand how to just look for the values I require changing.

Upvotes: 1

Views: 56

Answers (1)

Barmar
Barmar

Reputation: 781200

sed can either process named files or stdin, but not both. And the -i option can only be used when processing named files. So when you specify filename arguments, stdin is not used.

You should use the regexp as the address part of the sed command.

sed -i '/HN8 .* ATP/s_0[.]09_0.054_' topol.top

Upvotes: 3

Related Questions