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author | Roland Gaudig <roland.gaudig@weidmueller.com> | 2021-07-23 15:29:22 +0300 |
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committer | Tom Rini <trini@konsulko.com> | 2021-07-27 21:50:47 +0300 |
commit | 236d39bd10bd94545c5b0283ebc0999ddfd82344 (patch) | |
tree | 914675ea7f2708e85b4c40ec1e8f6934e2744db0 /doc/usage | |
parent | f4f8d8bb1abc79c4186ee8dc2ea536d62c6cb149 (diff) | |
download | u-boot-236d39bd10bd94545c5b0283ebc0999ddfd82344.tar.xz |
doc: usage: add description for setexpr command
Add usage for the setexpr command. It has been added to describe
mainly the new setexpr format string operation.
Signed-off-by: Roland Gaudig <roland.gaudig@weidmueller.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Diffstat (limited to 'doc/usage')
-rw-r--r-- | doc/usage/index.rst | 1 | ||||
-rw-r--r-- | doc/usage/setexpr.rst | 148 |
2 files changed, 149 insertions, 0 deletions
diff --git a/doc/usage/index.rst b/doc/usage/index.rst index 40b796a3a9..719b2c90b9 100644 --- a/doc/usage/index.rst +++ b/doc/usage/index.rst @@ -43,6 +43,7 @@ Shell commands reset sbi scp03 + setexpr size true ums diff --git a/doc/usage/setexpr.rst b/doc/usage/setexpr.rst new file mode 100644 index 0000000000..2e511b1290 --- /dev/null +++ b/doc/usage/setexpr.rst @@ -0,0 +1,148 @@ +.. SPDX-License-Identifier: GPL-2.0+ + +setexpr command +=============== + +Synopsis +-------- + +:: + + setexpr[.b, .w, .l .s] <name> [*]<value> <op> [*]<value2> + setexpr[.b, .w, .l] <name> [*]<value> + setexpr <name> fmt <format> [value]... + setexpr <name> gsub r s [t] + setexpr <name> sub r s [t] + +Description +----------- + +The setexpr command is used to set an environment variable to the result +of an evaluation. + +setexpr[.b, .w, .l .s] <name> [*]<value> <op> [*]<value2> + Set environment variable <name> to the result of the evaluated + expression specified by <op>. + +setexpr[.b, .w, .l] name [*]value + Load <value> into environment variable <name> + +setexpr name fmt <format> value + Set environment variable <name> to the result of the C like + format string <format> evaluation of <value>. + +setexpr name gsub <r> <s> [<t>] + For each substring matching the regular expression <r> in the + string <t>, substitute the string <s>. + The result is assigned to <name>. + If <t> is not supplied, use the old value of <name>. + +setexpr name sub <r> <s> [<t>] + Just like gsub(), but replace only the first matching substring + +The setexpr command takes the following arguments: + +format + This parameter contains a C or Bash like format string. + The number of arguments is limited to 4. + The following format types are supported: + + c + single character + d, i + decimal value + o + octal value + s + string + u + unsigned decimal value + x, X + hexadecimal value + '%' + no conversion, instead a % character will be written + + Backslash escapes: + + \" = double quote + \\ = backslash + \a = alert (bell) + \b = backspace + \c = produce no further output + \f = form feed + \n = new line + \r = carriage return + \t = horizontal tab + \v = vertical tab + \NNN = octal number (NNN is 0 to 3 digits) + +name + The name of the environment variable to be set + +op + '|' + name = value | value2 + '&' + name = value & value2 + '+' + name = value + value2 + (This is the only operator supported for strings. + It acts as concatenation operator on strings) + '^' + name = value ^ value2 + '-' + name = value - value2 + '*' + name = value * value2 + '/' + name = value / value2 + '%' + name = value % value2 + +r + Regular expression + +s + Substitution string + +t + string + +value + Can either be an integer value, a string. + If the pointer prefix '*' is given value is treated as memory address. + +value2 + See value + +Example +------- + +:: + + => setexpr foo fmt %d 0x100 + => echo $foo + 256 + => + + => setexpr foo fmt 0x%08x 63 + => echo $foo + 0x00000063 + => + + => setexpr foo fmt %%%o 8 + => echo $foo + %10 + => + +Configuration +------------- + +The setexpr gsub and sub operations are only available if CONFIG_REGEX=y. + +Return value +------------ + +The return value $? is set to 0 (true) if the operation was successful. + +If an error occurs, the return value $? is set to 1 (false). |