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| -rw-r--r-- | README | 41 | ||||
| -rw-r--r-- | doc/usage/cmdline.rst | 56 | ||||
| -rw-r--r-- | doc/usage/index.rst | 1 |
3 files changed, 57 insertions, 41 deletions
@@ -3510,47 +3510,6 @@ The signature of the callback functions is: The return value is 0 if the variable change is accepted and 1 otherwise. -Command Line Parsing: -===================== - -There are two different command line parsers available with U-Boot: -the old "simple" one, and the much more powerful "hush" shell: - -Old, simple command line parser: --------------------------------- - -- supports environment variables (through setenv / saveenv commands) -- several commands on one line, separated by ';' -- variable substitution using "... ${name} ..." syntax -- special characters ('$', ';') can be escaped by prefixing with '\', - for example: - setenv bootcmd bootm \${address} -- You can also escape text by enclosing in single apostrophes, for example: - setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off' - -Hush shell: ------------ - -- similar to Bourne shell, with control structures like - if...then...else...fi, for...do...done; while...do...done, - until...do...done, ... -- supports environment ("global") variables (through setenv / saveenv - commands) and local shell variables (through standard shell syntax - "name=value"); only environment variables can be used with "run" - command - -General rules: --------------- - -(1) If a command line (or an environment variable executed by a "run" - command) contains several commands separated by semicolon, and - one of these commands fails, then the remaining commands will be - executed anyway. - -(2) If you execute several variables with one call to run (i. e. - calling run with a list of variables as arguments), any failing - command will cause "run" to terminate, i. e. the remaining - variables are not executed. Note for Redundant Ethernet Interfaces: ======================================= diff --git a/doc/usage/cmdline.rst b/doc/usage/cmdline.rst new file mode 100644 index 0000000..b3dbdb8 --- /dev/null +++ b/doc/usage/cmdline.rst @@ -0,0 +1,56 @@ +.. SPDX-License-Identifier: GPL-2.0+ + +Command-line Parsing +==================== + +The command line is available in U-Boot proper, enabled by CONFIG_CMDLINE which +is on by default. It is not enabled in SPL. + +There are two different command-line parsers available with U-Boot: +the old "simple" one, and the much more powerful "hush" shell: + +Simple command-line parser +-------------------------- + +This takes very little code space and offers only basic features: + +- supports environment variables (through setenv / saveenv commands) +- several commands on one line, separated by ';' +- variable substitution using "... ${name} ..." syntax +- special characters ('$', ';') can be escaped by prefixing with '\', + for example:: + + setenv bootcmd bootm \${address} + +- You can also escape text by enclosing in single apostrophes, for example:: + + setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off' + +Hush shell +---------- + +This is similar to Bourne shell, with control structures like: + +- `if`... `then` ... `else`... `fi` +- `for`... `do` ... `done` +- `while` ... `do` ... `done` +- `until` ... `do` ... `done` + +Hush supports environment ("global") variables (through setenv / saveenv +commands) and local shell variables (through standard shell syntax +`name=value`); only environment variables can be used with the "run" command + +The Hush shell is enabled with `CONFIG_HUSH_PARSER`. + +General rules +------------- + +#. If a command line (or an environment variable executed by a "run" + command) contains several commands separated by semicolon, and + one of these commands fails, then the remaining commands will be + executed anyway. + +#. If you execute several variables with one call to run (i. e. + calling run with a list of variables as arguments), any failing + command will cause "run" to terminate, i. e. the remaining + variables are not executed. diff --git a/doc/usage/index.rst b/doc/usage/index.rst index 719b2c9..356f2a5 100644 --- a/doc/usage/index.rst +++ b/doc/usage/index.rst @@ -9,6 +9,7 @@ Use U-Boot fit netconsole partitions + cmdline Shell commands -------------- |