Replace Strings Using Sed And Regex

Question

I'm trying to uncomment file content using sed but with regex (for example: [0-9]{1,5})

# one two 12 # three four 34 # five six 56 

The following is working:

sed -e 's/# one two 12/one two 12/g' /file 

However, what I would like is to use regex pattern to replace all matches without entering numbers but keep the numbers in the result.

Answer 1

For complying sample question, simply

sed 's/^# //' file 

will suffice, but if there is a need to remove the comment only on some lines containing a particular regex, then you could use conditionnal address:

sed '/regex/s/^# //' file 

So every lines containing regex will be uncomented (if line begin with a #)

... where regex could be [0-9] as:

sed '/[0-9]/s/^# //' file 

will remove # at begin of every lines containing a number, or

sed '/[0-9]/s/^# \?//' file 

to make first space not needed: #one two 12, or even

sed '/[0-9]$/s/^# //' file 

will remove # at begin of lines containing a number as last character. Then

sed '/12$/s/^# //' file 

will remove # at begin of lines ended by 12. Or

sed '/\b\(two\|three\)\b/s/^# //' file 

will remove # at begin of lines containing word two or three.