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11da3403e9
For nearly all commands in U-Boot the '?' variable is handled the same way with 0 meaning success, 1 meaning any failure. Explain this in the general rules section of the cmdline documentation (with a link to a counter example) and then remove the redundant wording from most commands. We retain a section about the return value in a number of places where we are doing something such as always returning a specific value or we have useful additional information to go along with the normal return codes. Signed-off-by: Tom Rini <trini@konsulko.com> Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
150 lines
3.2 KiB
ReStructuredText
150 lines
3.2 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0+
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.. index::
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single: setexpr (command)
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setexpr command
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===============
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Synopsis
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--------
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::
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setexpr[.b, .w, .l .s] <name> [*]<value> <op> [*]<value2>
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setexpr[.b, .w, .l] <name> [*]<value>
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setexpr <name> fmt <format> [value]...
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setexpr <name> gsub r s [t]
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setexpr <name> sub r s [t]
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Description
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-----------
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The setexpr command is used to set an environment variable to the result
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of an evaluation.
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setexpr[.b, .w, .l .s] <name> [*]<value> <op> [*]<value2>
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Set environment variable <name> to the result of the evaluated
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expression specified by <op>.
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setexpr[.b, .w, .l] name [*]value
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Load <value> into environment variable <name>
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setexpr name fmt <format> value
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Set environment variable <name> to the result of the C like
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format string <format> evaluation of <value>.
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setexpr name gsub <r> <s> [<t>]
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For each substring matching the regular expression <r> in the
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string <t>, substitute the string <s>.
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The result is assigned to <name>.
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If <t> is not supplied, use the old value of <name>.
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If no substring matching <r> is found in <t>, assign <t> to <name>.
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setexpr name sub <r> <s> [<t>]
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Just like gsub(), but replace only the first matching substring
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The setexpr command takes the following arguments:
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format
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This parameter contains a C or Bash like format string.
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The number of arguments is limited to 4.
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The following format types are supported:
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c
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single character
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d, i
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decimal value
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o
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octal value
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s
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string
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u
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unsigned decimal value
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x, X
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hexadecimal value
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'%'
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no conversion, instead a % character will be written
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Backslash escapes:
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\" = double quote
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\\ = backslash
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\a = alert (bell)
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\b = backspace
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\c = produce no further output
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\f = form feed
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\n = new line
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\r = carriage return
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\t = horizontal tab
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\v = vertical tab
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\NNN = octal number (NNN is 0 to 3 digits)
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name
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The name of the environment variable to be set
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op
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'|'
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name = value | value2
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'&'
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name = value & value2
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'+'
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name = value + value2
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(This is the only operator supported for strings.
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It acts as concatenation operator on strings)
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'^'
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name = value ^ value2
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'-'
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name = value - value2
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'*'
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name = value * value2
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'/'
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name = value / value2
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'%'
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name = value % value2
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r
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Regular expression
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s
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Substitution string
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t
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string
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value
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Can either be an integer value, a string.
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If the pointer prefix '*' is given value is treated as memory address.
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value2
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See value
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Example
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-------
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::
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=> setexpr foo fmt %d 0x100
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=> echo $foo
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256
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=>
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=> setexpr foo fmt 0x%08x 63
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=> echo $foo
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0x00000063
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=>
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=> setexpr foo fmt %%%o 8
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=> echo $foo
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%10
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=>
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Configuration
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-------------
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* The *setexpr* command is only available if CMD_SETEXPR=y.
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* The *setexpr fmt* sub-command is only available if CMD_SETEXPR_FMT=y.
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* The *setexpr gsub* and *setexpr sub* sub-commands are only available
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if CONFIG_REGEX=y. For an overview of the supported regex syntax,
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see :doc:`test`.
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