| Simon Glass | cfc9010 | 2021-07-24 09:03:36 -0600 | [diff] [blame] | 1 | .. SPDX-License-Identifier: GPL-2.0+ |
| 2 | |
| 3 | Command-line Parsing |
| 4 | ==================== |
| 5 | |
| 6 | The command line is available in U-Boot proper, enabled by CONFIG_CMDLINE which |
| 7 | is on by default. It is not enabled in SPL. |
| 8 | |
| 9 | There are two different command-line parsers available with U-Boot: |
| 10 | the old "simple" one, and the much more powerful "hush" shell: |
| 11 | |
| 12 | Simple command-line parser |
| 13 | -------------------------- |
| 14 | |
| 15 | This takes very little code space and offers only basic features: |
| 16 | |
| 17 | - supports environment variables (through setenv / saveenv commands) |
| 18 | - several commands on one line, separated by ';' |
| 19 | - variable substitution using "... ${name} ..." syntax |
| 20 | - special characters ('$', ';') can be escaped by prefixing with '\', |
| 21 | for example:: |
| 22 | |
| 23 | setenv bootcmd bootm \${address} |
| 24 | |
| 25 | - You can also escape text by enclosing in single apostrophes, for example:: |
| 26 | |
| 27 | setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off' |
| 28 | |
| 29 | Hush shell |
| 30 | ---------- |
| 31 | |
| 32 | This is similar to Bourne shell, with control structures like: |
| 33 | |
| 34 | - `if`... `then` ... `else`... `fi` |
| 35 | - `for`... `do` ... `done` |
| 36 | - `while` ... `do` ... `done` |
| 37 | - `until` ... `do` ... `done` |
| 38 | |
| 39 | Hush supports environment ("global") variables (through setenv / saveenv |
| 40 | commands) and local shell variables (through standard shell syntax |
| 41 | `name=value`); only environment variables can be used with the "run" command |
| 42 | |
| 43 | The Hush shell is enabled with `CONFIG_HUSH_PARSER`. |
| 44 | |
| 45 | General rules |
| 46 | ------------- |
| 47 | |
| 48 | #. If a command line (or an environment variable executed by a "run" |
| 49 | command) contains several commands separated by semicolon, and |
| 50 | one of these commands fails, then the remaining commands will be |
| 51 | executed anyway. |
| 52 | |
| 53 | #. If you execute several variables with one call to run (i. e. |
| 54 | calling run with a list of variables as arguments), any failing |
| 55 | command will cause "run" to terminate, i. e. the remaining |
| 56 | variables are not executed. |
| Simon Glass | 6e0cd52 | 2021-07-24 09:03:37 -0600 | [diff] [blame^] | 57 | |
| 58 | Representing numbers |
| 59 | -------------------- |
| 60 | |
| 61 | Most U-Boot commands use hexadecimal (hex) as the default base, for convenient |
| 62 | use of addresses, for example:: |
| 63 | |
| 64 | => md 1000 6 |
| 65 | 00001000: 2c786f62 00697073 03000000 0c000000 box,spi......... |
| 66 | 00001010: 67020000 00000000 ...g.... |
| 67 | |
| 68 | There is no need to add a `0x` prefix to the arguments and the output is shown |
| 69 | in hex also, without any prefixes. This helps to avoid clutter. |
| 70 | |
| 71 | Some commands use decimal where it is more natural:: |
| 72 | |
| 73 | => i2c dev 0 |
| 74 | Setting bus to 0 |
| 75 | => i2c speed |
| 76 | Current bus speed=400000 |
| 77 | => i2c speed 100000 |
| 78 | Setting bus speed to 100000 Hz |
| 79 | |
| 80 | In some cases the default is decimal but it is possible to use octal if that is |
| 81 | useful:: |
| 82 | |
| 83 | pmic dev pmic@41 |
| 84 | dev: 1 @ pmic@41 |
| 85 | => pmic write 2 0177 |
| 86 | => pmic read 2 |
| 87 | 0x02: 0x00007f |