how to find a pattern in file entry, remove leading hash and redirect all entries to file

Question

Looking for the syntax to find a pattern in a file and remove the leading character from only that pattern.

For example, find -16 and remove the # and save it to file.

Tried grep 12345-16 testfile2 | sed -e "s/^#//g" which works but need to capture all entries into the input file.

Example:

From this:

something   here 12345-14
something   here 12345-15
# something here 12345-16

to this:

something   here 12345-14
something   here 12345-15
something   here 12345-16

suggestions would be much appreciated.

Answer 1

You can do it with just sed alone.

sed '/12345-16/s/^# *//' file

You can use -i option of sed to make in-file changes. /../ in front of sed is a regex which only makes changes on lines that has that pattern. All remaining lines will not be touched and be printed out as is.

You don't need g for global here since you are only removing the leading #. I have added a pattern of ^# * which means # or # followed by spaces at the start of the line. You can create your own pattern based on the structure of your file.