doc: usage: Add general rule for $?

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>
This commit is contained in:
Tom Rini 2025-10-24 10:02:57 -06:00
parent 1f6da608c3
commit 11da3403e9
45 changed files with 6 additions and 245 deletions

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@ -90,8 +90,3 @@ Configuration
-------------
The command is available if CONFIG_CMD_ARMFFA=y and CONFIG_ARM_FFA_TRANSPORT=y.
Return value
------------
The return value $? is 0 (true) on success, 1 (false) on failure.

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@ -115,8 +115,3 @@ Configuration
-------------
The bdinfo command is available if CONFIG_CMD_BDI=y.
Return code
-----------
The return code $? is 0 (true).

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@ -99,8 +99,3 @@ Configuration
-------------
The bind command is only available if CONFIG_CMD_BIND=y.
Return code
-----------
The return code $? is 0 (true) on success and 1 (false) on failure.

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@ -69,9 +69,3 @@ Configuration
-------------
The blkcache command is only available if CONFIG_CMD_BLOCK_CACHE=y.
Return code
-----------
If the command succeeds, the return code $? is set 0 (true). In case of an
error the return code is set to 1 (false).

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@ -45,8 +45,3 @@ Configuration
-------------
The cat command is only available if CONFIG_CMD_CAT=y.
Return value
------------
The return value $? is set to 0 (true) if the file is readable, otherwise it returns a non-zero error code.

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@ -70,8 +70,3 @@ compiled::
modern
=> cli set old
Want to set current parser to old, but its code was not compiled!
Return value
------------
The return value $? indicates whether the command succeeded.

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@ -22,8 +22,3 @@ Configuration
-------------
The cls command is only available if CONFIG_CMD_CLS=y.
Return value
------------
The return value $? is 0 (true) on success and 1 (false) on failure.

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@ -79,9 +79,3 @@ Configuration
The cp command is available if CONFIG_CMD_MEMORY=y. Support for 64 bit words
(cp.q) is only available on 64-bit targets. Copying to flash depends on
CONFIG_MTD_NOR_FLASH=y.
Return value
------------
The return value $? is set to 0 (true) if the command was successfully,
1 (false) otherwise.

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@ -93,9 +93,3 @@ Configuration
-------------
The cpu command is available if CONFIG_CMD_CPU=y.
Return code
-----------
The return value $? is set to 0 (true) if the command is successful,
1 (false) otherwise.

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@ -25,11 +25,6 @@ Configuration
The cpuid command is only available on x86.
Return value
------------
The return value $? is 0 (true).
Example
-------

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@ -47,9 +47,3 @@ Configuration
The dmareset command is only available if CONFIG_CMD_C5_PL330_DMA=y in
"Shell scripting commands".
Return value
------------
If the command succeeds, the return value $? is set to 0 (true).
If an error occurs, the return value $? is set to 1 (false).

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@ -64,9 +64,3 @@ Configuration
The ebtupdate command is only available if CONFIG_CMD_EBTUPDATE=y and
only on Tegra 2 and Tegra 3 configurations.
Return value
------------
The return value $? is set to 0 (true) if everything went successfully. If an
error occurs, the return value $? is set to 1 (false).

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@ -46,9 +46,3 @@ Configuration
-------------
The fatinfo command is only available if CONFIG_CMD_FAT=y.
Return value
------------
The return value $? is set to 0 (true) if the partition is a FAT partition.
Otherwise it is set to 1 (false).

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@ -66,8 +66,3 @@ address and expand it to 0xf000 in size::
Working FDT set to 10000
=> md 10000 4
00010000: edfe0dd0 00f00000 78000000 7c270000 ...........x..'|
Return value
------------
The return value $? indicates whether the command succeeded.

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@ -54,9 +54,3 @@ Configuration
-------------
The command is only available if CONFIG_CONSOLE_TRUETYPE=y.
Return value
------------
The return value $? is 0 (true) if the command completes.
The return value is 1 (false) if the command fails.

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@ -168,9 +168,3 @@ Configuration
The fuse commands are available if CONFIG_CMD_FUSE=y.
The fuse writebuff command is available if CONFIG_CMD_FUSE_WRITEBUFF=y.
Return code
-----------
The return value $? is set to 0 (true) if the command is successful,
1 (false) otherwise.

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@ -127,9 +127,3 @@ Configuration
The *gpio* command is only available if CONFIG_CMD_GPIO=y.
The *gpio read* command is only available if CONFIG_CMD_GPIO_READ=y.
Return value
------------
If the command succeds the return value $? is set to 0. If an error occurs, the
return value $? is set to 1.

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@ -111,9 +111,3 @@ Unbind a device::
=> host info
dev blocks label path
1 2048 fat 1MB.fat32.img
Return value
------------
The return value $? indicates whether the command succeeded.

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@ -129,12 +129,6 @@ Configuration
The ``i3c`` command is only available if CONFIG_CMD_I3C=y.
Return value
------------
If the command succeeds, the return value ``$?`` is set to 0. If an error
occurs, the return value ``$?`` is set to 1.
Note
----

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@ -76,9 +76,3 @@ Configuration
The imxtract command is only available if CONFIG_CMD_XIMG=y. Support for FIT
images requires CONFIG_FIT=y. Support for legacy U-Boot images requires
CONFIG_LEGACY_IMAGE_FORMAT=y.
Return value
------------
On success the return value $? of the command is 0 (true). On failure the
return value is 1 (false).

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@ -66,8 +66,3 @@ Configuration
-------------
The command is only available if CONFIG_CMD_LOADB=y.
Return value
------------
The return value $? is 0 (true) on success, 1 (false) on error.

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@ -43,10 +43,3 @@ Configuration
-------------
The command is only available if CONFIG_CMD_LOADM=y.
Return value
------------
The return value $? is set 0 (true) if the loading is succefull, and
is set to 1 (false) in case of error.

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@ -92,8 +92,3 @@ Configuration
The command is only available if CONFIG_CMD_LOADS=y. The parameter to set the
baud rate is only available if CONFIG_SYS_LOADS_BAUD_CHANGE=y
Return value
------------
The return value $? is 0 (true) on success, 1 (false) otherwise.

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@ -73,8 +73,3 @@ The command is only available if CONFIG_CMD_LOADB=y.
Initial timeout in seconds while waiting for transfer is configured by
config option CMD_LOADXY_TIMEOUT or by env variable $loadxy_timeout.
Setting it to 0 means infinite timeout.
Return value
------------
The return value $? is 0 (true) on success, 1 (false) otherwise.

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@ -70,8 +70,3 @@ The command is only available if CONFIG_CMD_LOADB=y.
Initial timeout in seconds while waiting for transfer is configured by
config option CMD_LOADXY_TIMEOUT or by env variable $loadxy_timeout.
Setting it to 0 means infinite timeout.
Return value
------------
The return value $? is 0 (true) on success, 1 (false) otherwise.

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@ -38,11 +38,6 @@ Configuration
The msr command is only available on x86.
Return value
------------
The return value $? is 0 (true).
Example
-------

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@ -62,8 +62,3 @@ Configuration
-------------
The mtest command is enabled by CONFIG_CMD_MEMTEST=y.
Return value
------------
The return value $? is 0 (true) if the command succeeds, 1 (false) otherwise.

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@ -63,8 +63,3 @@ Configuration
-------------
The optee command is enabled by CONFIG_OPTEE=y and CONFIG_CMD_OPTEE=y.
Return value
------------
The return value $? is 0 (true) if the command succeeds, 1 (false) otherwise.

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@ -223,9 +223,3 @@ This shows looking at a device with multiple partition tables::
type: ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
guid: a0891d7e-b930-4513-94da-f629dbd637b2
=>
Return value
------------
The return value $? is set to 0 (true) if the command succededd. If an
error occurs, the return value $? is set to 1 (false).

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@ -48,9 +48,3 @@ Note that complex prompts require proper quoting:
Usage:
pause [prompt] - Wait until users presses any key. [prompt] can be used to customize the message.
Return value
------------
The return value $? is always set to 0 (true), unless invoked in an invalid
manner.

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@ -90,9 +90,3 @@ Configuration
-------------
The pinmux command is only available if CONFIG_CMD_PINMUX=y.
Return value
------------
The return value $? is set to 0 (true) if the command succeded and to 1 (false)
otherwise.

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@ -83,9 +83,3 @@ Configuration
-------------
The ``pwm`` command is only available if CONFIG_CMD_PWM=y.
Return value
------------
If the command succeeds, the return value ``$?`` is set to 0. If an error occurs, the
return value ``$?`` is set to 1.

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@ -84,8 +84,3 @@ Configuration
The command is only available if CONFIG_CMD_SAVES=y. The parameter to set the
baud rate is only available if CONFIG_SYS_LOADS_BAUD_CHANGE=y
Return value
------------
The return value $? is 0 (true) on success, 1 (false) otherwise.

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@ -119,11 +119,4 @@ Configuration
The scmi command is only available if CONFIG_CMD_SCMI=y.
Default n because this command is mainly for debug purpose.
Return value
------------
The return value ($?) is set to 0 if the operation succeeded,
1 if the operation failed or -1 if the operation failed due to
a syntax error.
.. _`SCMI specification`: https://developer.arm.com/documentation/den0056/e/?lang=en

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@ -147,10 +147,3 @@ Configuration
* The *setexpr gsub* and *setexpr sub* sub-commands are only available
if CONFIG_REGEX=y. For an overview of the supported regex syntax,
see :doc:`test`.
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).

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@ -35,9 +35,3 @@ Configuration
-------------
The size command is only available if CONFIG_CMD_FS_GENERIC=y.
Return value
------------
The return value $? is set to 0 (true) if the command succeded and to 1 (false)
otherwise.

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@ -86,8 +86,3 @@ Configuration
-------------
The command is only available if CONFIG_CMD_SMBIOS=y.
Return value
------------
The return value $? is 0 (true) on success, 1 (false) otherwise.

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@ -56,8 +56,3 @@ Configuration
-------------
The sound command is enabled by CONFIG_CMD_SOUND=y.
Return value
------------
The return value $? is 0 (true) if the command succeeds, 1 (false) otherwise.

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@ -188,9 +188,3 @@ The FIT image file format requires CONFIG_FIT=y.#
The legacy U-Boot image file format requires CONFIG_LEGACY_IMAGE_FORMAT=y.
On hardened systems support for the legacy U-Boot image format should be
disabled as these images cannot be signed and verified.
Return value
------------
If the scripts is executed successfully, the return value $? is 0 (true).
Otherwise it is 1 (false).

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@ -45,9 +45,3 @@ Configuration
-------------
The *temperature* command is only available if CONFIG_CMD_TEMPERATURE=y.
Return value
------------
The return value $? is set to 0 (true) if the command succeeded and to 1 (false)
otherwise.

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@ -79,8 +79,3 @@ after which an ACK response is required. The window size defaults to 1.
If CONFIG_TFTP_TSIZE=y, the progress bar is limited to 50 '#' characters.
Otherwise an '#' is written per UDP package which may decrease performance.
Return value
------------
The return value $? is 0 (true) on success and 1 (false) otherwise.

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@ -91,8 +91,3 @@ Configuration
-------------
The unbind command is only available if CONFIG_CMD_BIND=y.
Return code
-----------
The return code $? is 0 (true) on success and 1 (false) on failure.

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@ -73,8 +73,3 @@ Configuration
-------------
The command is only available if CONFIG_CMD_WDT=y.
Return value
------------
The return value $? is 0 if the command succeeds, 1 upon failure.

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@ -184,8 +184,3 @@ CONFIG_WGET_CACERT=y (for the wget cacert command).
TCP Selective Acknowledgments in the legacy network stack can be enabled via
CONFIG_PROT_TCP_SACK=y. This will improve the download speed. Selective
Acknowledgments are enabled by default with lwIP.
Return value
------------
The return value $? is 0 (true) on success and 1 (false) otherwise.

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@ -55,6 +55,12 @@ General rules
command will cause "run" to terminate, i. e. the remaining
variables are not executed.
#. The variable ``$?`` will be set as the return value of any command. The
possible values are 0 on success or 1 on any error e. g. invalid syntax or
failure of the command. Any exceptions to this are documented by the
specific command, e.g. the :doc:`for command <cmd/for>` sets ``$?`` based on
the last command run within the loop.
Representing numbers
--------------------