Add leading 0 in sed substitution

Question

I have input data:

foo 24
foobar 5 bar
bar foo 125

and I\'d like to have output:

foo 024
foobar 005 bar
bar foo 125
         


        

Answer 1

Use two substitute commands: the first one will search for one digit and will insert two zeroes just before, and the second one will search for a number with two digits and will insert one zero just before. GNU sed is needed because I use the word boundary command to search for digits (\b).

sed -e 's/\b[0-9]\b/00&/g; s/\b[0-9]\{2\}\b/0&/g' infile

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EDIT to add a test:

Content of infile:

foo 24 9
foo 645 bar 5 bar
bar foo 125

Run previous command with following output:

foo 024 009
foo 645 bar 005 bar
bar foo 125