Using /bin/bash on RHEL 5.8 and I want to automate editing a file. I need the script to search the file and replace a line in the file. Line example:

Other line
Current date 01121990
Other line

Search for this line and replace the date string with a predetermined date. I can't echo to a new file and enter in my date since this file will be copied from a server-specific file. Thanks!

  • 2
    sed would be the tool of choice here...
    – jasonwryan
    Mar 19, 2016 at 23:16

2 Answers 2

your_date='your desired date'
sed -i "s/^Current date.*/Current date ${your_date}/" /path/to/file

That's the easiest way. This assumes that all lines that contains a date to replace also are the only lines to start with 'Current date'.

Note that the user level that runs this command must also have permission to edit that file.

-i means inline edit, which means you are editing the file directly.

^Current date.*

Means all lines starting with: Current date and ending in anything. In other words, replace the entire line with what is in the second /.../ part of the sed thing.

Double " are used around the sed statement so that variables will be used as variables, not strings.

  • Thanks Lizardx that's exactly what I need, tested it and it works great
    – Paul
    Mar 20, 2016 at 0:52
  • great glad to hear it.
    – Lizardx
    Mar 20, 2016 at 2:39

ed can do in-place editing of files as well! The inode number of the edited file remains unchanged.

your_date='your desired date'
ls -i "$file"
printf '%s\n' H ",g/^Current date.*/s//${your_date}/" wq | ed -s "$file"
ls -i "$file"

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