Swap value in column 1
In GNU sed you could do like this:
sed -e 's/^23\>/X/' file.txtOr using perl:
perl -pe 's/^23\b/X/' file.txtOr using awk:
awk '{ if ($1 == 23) sub("23", "X"); print }' file.txtIf you want to update the file after the replacement, then you can use any of these commands:
sed -i -e 's/^23\>/X/' file.txtperl -pi -e 's/^23\b/X/' file.txt
Do you have access to any scripting languages? a perl or python script to replace a line start followed by 23 with a line start followed by X would be pretty simple.
see this answer: Find and Replace Inside a Text File from a Bash Command
so something like...
perl -pi -e 's/^23\s/X /g' /tmp/file.txt