Why is sed not recognizing \t as a tab?

Question

sed \"s/\\(.*\\)/\\t\\1/\" $filename > $sedTmpFile && mv $sedTmpFile $filename

I am expecting this sed script to insert a <

Answer 1

I used this on Mac:

sed -i '' $'$i\\\n\\\thello\n' filename

Used this link for reference

Answer 2

You don't need to use sed to do a substitution when in actual fact, you just want to insert a tab in front of the line. Substitution for this case is an expensive operation as compared to just printing it out, especially when you are working with big files. Its easier to read too as its not regex.

eg using awk

awk '{print "\t"$0}' $filename > temp && mv temp $filename

Answer 3

TAB=$(printf '\t')
sed "s/${TAB}//g" input_file

It works for me on Red Hat, which will remove tabs from the input file.

Answer 4

Use $(echo '\t'). You'll need quotes around the pattern.

Eg. To remove a tab:

sed "s/$(echo '\t')//"

Answer 5

Not all versions of sed understand \t. Just insert a literal tab instead (press Ctrl-V then Tab).