echo —
write arguments to the standard
output
The echo utility writes any specified
operands, separated by single blank
(‘ ’) characters and followed
by a newline (‘\n’) character, to the
standard output.
The following option is available:
-n
- Do not print the trailing newline character.
The end-of-options marker
-- is not recognized and
written literally.
The newline may also be suppressed by appending
‘\c’ to the end of the string, as is
done by iBCS2 compatible systems. Note that the -n
option as well as the effect of ‘\c’
are implementation-defined in IEEE Std 1003.1-2001
(“POSIX.1”) as amended by Cor. 1-2002. For portability,
echo should only be used if the first argument does
not start with a hyphen (‘-’) and does
not contain any backslashes (‘\’). If
this is not sufficient,
printf(1) should be used.
Most shells provide a builtin echo command
which tends to differ from this utility in the treatment of options and
backslashes. Consult the
builtin(1) manual page.
The echo utility exits 0 on
success, and >0 if an error occurs.
Special treatment of options and backslashes:
$ /bin/echo "-hello\tworld"
-helloworld
Avoid new line character:
$ /bin/echo -n hello;/bin/echo world
helloworld
Or to achieve the same result:
$ /bin/echo "hello\c";/bin/echo world
helloworld
The echo utility conforms to
IEEE Std 1003.1-2001 (“POSIX.1”) as
amended by Cor. 1-2002.
The echo command appeared in
Version 2 AT&T UNIX.
The echo command behaves differently with
regards to the built-in echo shell command in a
number of ways including escaped characters handling. It also differs in
behavior between different systems hence complicating writing portable
scripts. It is advised to use the
printf(1) command to avoid these shortcomings.