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u-boot/doc/usage/cmd/echo.rst
Bin Meng 34e452dd02 doc: usage: Group all shell command docs into cmd/ sub-directory
Currently all shell command docs are put in the doc/usage root.
Let's group them into cmd/ sub-directory.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
2022-03-31 19:06:16 +02:00

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echo command
============
Synopsis
--------
::
echo [-n] [args ...]
Description
-----------
The echo command prints its arguments to the console separated by spaces.
-n
Do not print a line feed after the last argument.
args
Arguments to be printed. The arguments are evaluated before being passed to
the command.
Examples
--------
Strings are parsed before the arguments are passed to the echo command:
::
=> echo "a" 'b' c
a b c
=>
Observe how variables included in strings are handled:
::
=> setenv var X; echo "a)" ${var} 'b)' '${var}' c) ${var}
a) X b) ${var} c) X
=>
-n suppresses the line feed:
::
=> echo -n 1 2 3; echo a b c
1 2 3a b c
=> echo -n 1 2 3
1 2 3=>
A more complex example:
::
=> for i in a b c; do for j in 1 2 3; do echo -n "${i}${j}, "; done; echo; done;
a1, a2, a3,
b1, b2, b3,
c1, c2, c3,
=>
Return value
------------
The return value $? is always set to 0 (true).