From 750ff62da7e76e2c71a782853c52c0a863b40d5d Mon Sep 17 00:00:00 2001 From: Heinrich Schuchardt Date: Thu, 21 Jan 2021 17:33:44 +0100 Subject: [PATCH] doc: document echo command Provide a man-page for the echo command. Signed-off-by: Heinrich Schuchardt Reviewed-by: Simon Glass --- doc/usage/echo.rst | 65 +++++++++++++++++++++++++++++++++++++++++++++ doc/usage/index.rst | 1 + 2 files changed, 66 insertions(+) create mode 100644 doc/usage/echo.rst diff --git a/doc/usage/echo.rst b/doc/usage/echo.rst new file mode 100644 index 0000000000..861abdfd1e --- /dev/null +++ b/doc/usage/echo.rst @@ -0,0 +1,65 @@ +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). diff --git a/doc/usage/index.rst b/doc/usage/index.rst index 6f49652758..317db3b449 100644 --- a/doc/usage/index.rst +++ b/doc/usage/index.rst @@ -17,6 +17,7 @@ Shell commands bootefi bootmenu button + echo exit for mbr -- 2.39.5