The printf command

The printf command works like echo, except the first argument you provide to it is a format string:

$ printf '%s\n' 'Hello!'
Hello!

Notice that we had to put the format string in single quotes, to prevent the backslash from having special meaning to the shell. Notice also that we didn't have to use double quotes to get the newline from \n; the printf command did that for us.

You can use printf in much the same way you would use a printf() function in other languages, such as C. It supports most of the same format specifications as the printf(1) system command; you can type man 1 printf to see a list.

It's easier to print tricky strings with printf, where echo might struggle:

$ printf '%s\n' -n
-n
$ string=-n
$ printf '%s\n' "$string"
-n

You should always choose printf over echo in scripts, even though it's a little more typing.

printf also has a useful property where it will repeat the format string as necessary for each argument you provide it. This is a convenient way to print a list of arguments on individual lines:

$ printf '%s\n' foo bar baz
foo
bar
baz

Note that we got three instances of the string-newline pattern from one format string.

Finally, Bash's printf has a %q pattern that can be used to quote special characters in a string with backslashes, so it can be reused safely in the shell. If you follow good quoting practices, you are unlikely to need this a lot in Bash, but it's useful to know it's there:

bash$ printf '%q\n' 'Watch out for thi$ $tring; it \has\ nasty character$!'
Watch\ out\ for\ thi\$\ \$tring\;\ it\ \\has\\\ nasty\ character\$\!