sed Tip: Delete All Blank White Spaces

   foo
   bar
  foobar 

How can I delete all leading and/or trailing blank spaces, tab from each line using sed command?

1. Perl.
2. Python.
3. Awk and friends.

Perl example

The syntax is:

perl -lape 's/\s+//sg' input > output

Sample outputs:

foo
bar
foobar

Or use -pie syntax to update file:

cat input
perl -lapi -e 's/\s+|^\n//sg'  input
cat input

See perl man page for more information.

Sed example

The syntax is:

sed -e 's/^[ \t]*//' -e 's/[ \t]*$//' input > output

OR updated file in a single go with the -i option:

sed -i -e 's/^[ \t]*//' -e 's/[ \t]*$//' input

See sed command man page for more information.

Awk example

The syntax is

awk '{$1=$1}{ print }' input > output

You can also use gsub() substring matching the regular expression function. See awk man page for more information.