The echo command writes its command-line arguments and a newline to the standard output. Shell scripts use echo for sending text to the terminal, down a pipe, and into a file. You can use echo on the command line to show the value of a , to see how filename wildcards will expand without doing anything else to those files, or :
The printf command gives you more formatting control.
The original echo , and the csh echo which acts like it, have just one option. The -n option tells echo not to print a newline after the message. Shell scripts use -n to send a question to a user and leave the cursor at the end of the message:
echo -n "Enter your name: "
(The space at the end makes the prompt look better. The quotes make the shell pass that space on to echo .)
Newer versions of echo
check their arguments for a backslash (
In this version of echo
echo "Enter your name: \c"
Your online echo (or csh ) manual page should tell you which version you have and list any escape sequences.
cat << END The answer is: $
bash users are lucky: That shell's echo has a -e option that enables backslash interpretation, and a -E option that disables it.
Because printf isn't built into any shells I know of, it's more portable than the crazy set of echo s. If we had printf and the old echo , life would be easier. Article 46.10 shows a way to make echo portable.
The C shell echo works differently from other versions. For example, to make an empty line with the standard echo , don't give any arguments. (This is usually done for readability - to put blank lines between other output.) Standard echo will just print a newline:
Without arguments, the C shell echo doesn't print the newline. To get a newline, you have to give an empty argument:
To use the standard echo from the C shell, type /bin/echo instead.
echo writes to standard output. Error messages in shell scripts should be written to the standard error so that of standard output doesn't accidentally capture the message. The Bourne shell will move echo 's output to standard error:
echo "progname: choke wheeze complain" 1>&2
The C shell can't do that - which is another reason.