236d39bd10
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>
149 lines
3.0 KiB
ReStructuredText
149 lines
3.0 KiB
ReStructuredText
.. 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).
|