tr command - how to replace the string "\n" with an actual newline (\n)

Question

I would like to use the tr command to replace all occurrences of the string "\n" with a new line (\n).

I tried tr '\\n' '\n' but this just seems to match any '\' and any 'n'

Conducive

As @Aniket points out, tr won't work for this - it replaces a single byte with a single byte and can't deal with multi-byte strings ("\n"). You'll need sed, awk or another tool to accomplish this. – Herwig

Answer 1

Here's how to do it with sed:

sed 's/\\n/\n/g'

Example usage:

To replace all occurrences of \n in a file in-place:

sed -i 's/\\n/\n/g' input_filename

To replace all occurrences of \n through a pipe, and save into another file

cat file1 file2 file3 file4 | sed 's/\\n/\n/g' > output_file

Flake

This does not work for me on bash 3 on OS X. It replaces \n with n. – Xi

@Xi You need the GNU version of sed for this to work. brew install gnu-sed then either use the gsed command or set your $PATH so that the GNU version takes precedence: https://mcmap.net/q/64805/-how-to-use-gnu-sed-on-mac-os-10-10-39-brew-install-default-names-39-no-longer-supported – Congeal

The Bash version makes no difference, but the sed version does. It is unfortunate that a nonportable version got accepted. – Grapple

See the proposed duplicate for portability notes and a couple of portable alternatives. – Grapple

I couldn't get this going with gsed on OSX; had to use the Perl solution in the answer below this one. – Panicstricken

Answer 2

The Perl solution is similar to the sed solution from sampson-chen:

perl -pe 's/\\n/\n/g'

Examples:

Input file with literal \n (not newlines):

$ cat test1.txt          
foo\nbar\n\nbaz

Replace all literal occurrences of \n with actual newlines, print into STDOUT:

$ perl -pe 's/\\n/\n/g' test1.txt
foo
bar

baz

Same, change the input file in-place, saving the backup into test1.txt.bak:

$ perl -i.bak -pe 's/\\n/\n/g' test1.txt

The Perl one-liner uses these command line flags:
-e : Tells Perl to look for code in-line, instead of in a file.
-p : Loop over the input one line at a time, assigning it to $_ by default. Add print $_ after each loop iteration.
-i.bak : Edit input files in-place (overwrite the input file). Before overwriting, save a backup copy of the original file by appending to its name the extension .bak.

SEE ALSO:
perldoc perlrun: how to execute the Perl interpreter: command line switches
perldoc perlre: Perl regular expressions (regexes)

Angrist

Answer 3

I had a similar issue where I wanted to replace '\n' with new line on Mac BigSur

Input:

-----BEGIN CERTIFICATE-----\\nMIGcz......\naLRn\\nyxiJdo=\\n-----END CERTIFICATE-----

Expected output:

-----BEGIN CERTIFICATE-----
MIGcz......
aLRn
yxiJdo=
-----END CERTIFICATE-----

Sed, perl none worked for me. But a simple 'tr' command was useful.

echo -----BEGIN CERTIFICATE-----\\nMIGcz......\\naLRn\\nyxiJdo=\\n-----END CERTIFICATE----- | tr '\' '\n'

Lindly

This is broken, it replaces \ with a newline and leaves the n. – Grapple