summaryrefslogtreecommitdiffstats
path: root/README
diff options
context:
space:
mode:
Diffstat (limited to 'README')
-rw-r--r--README48
1 files changed, 45 insertions, 3 deletions
diff --git a/README b/README
index ecc087ad91..e9b714567f 100644
--- a/README
+++ b/README
@@ -2048,6 +2048,48 @@ Please note that changes to some configuration parameters may take
only effect after the next boot (yes, that's just like Windoze :-).
+Command Line Parsing:
+=====================
+
+There are two different command line parsers available with U-Boot:
+the old "simple" one, and the much more pwerful "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 af variables as arguments), any failing
+ command will cause "run" to terminate, i. e. the remaining
+ variables are not executed.
+
Note for Redundant Ethernet Interfaces:
=======================================
@@ -2563,9 +2605,9 @@ Minicom warning:
================
Over time, many people have reported problems when trying to used the
-"minicom" terminal emulation program for serial download. I (wd)
-consider minicom to be broken, and recommend not to use it. Under
-Unix, I recommend to use CKermit for general purpose use (and
+"minicom" terminal emulation program for serial download. I (wd)
+consider minicom to be broken, and recommend not to use it. Under
+Unix, I recommend to use C-Kermit for general purpose use (and
especially for kermit binary protocol download ("loadb" command), and
use "cu" for S-Record download ("loads" command).
OpenPOWER on IntegriCloud