Using sed with multiple conditions-CodePudding

I have a .spec file that has a lines such as the following:

Requires: rpm_name           = 1.0.0
Requires: longer_rpm_name    = 1.0.1

I am putting together a script that will write to the .spec file and update the rpm versions with their respective newer versions.

Using sed I can do something like sed -i 's/Requires: rpm_name.*/Requires: rpm_name = 2.0.0'. This will result in the following:

Requires: rpm_name = 2.0.0
Requires: longer_rpm_name    = 1.0.1

Rather than replace the entire line I would like to simply replace the version number that follows the = character such that the formatting of the lines remains the same. I would like:

Requires: rpm_name          = 2.0.0
Requires: longer_rpm_name   = 1.0.1

I'd like sed to find the line starting with Requires: rpm_name and the only replace the version number instead of the entire line. Is this possible?

CodePudding user response：

Use an address specification at the beginning of the command to match the line. Then use a regexp in the s command to replace just the number at the end.

sed -i '/^Requires: rpm_name/s/[0-9.]*$/2.0.0/'

CodePudding user response：

Remember the part until the equal sign

sed -ri 's/(Requires: rpm_name.*)=/\1= 2.0.0/'

CodePudding user response：

Using sed

$ sed 's/\(\<rpm_name \ =\).*/\1 2.0.0/' input_file
Requires: rpm_name           = 2.0.0
Requires: longer_rpm_name    = 1.0.1