mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-12-24 20:13:39 +00:00
66 lines
1.2 KiB
ReStructuredText
66 lines
1.2 KiB
ReStructuredText
|
for command
|
||
|
|
===========
|
||
|
|
|
||
|
|
Synopis
|
||
|
|
-------
|
||
|
|
|
||
|
|
::
|
||
|
|
|
||
|
|
for <variable> in <items>; do <commands>; done
|
||
|
|
|
||
|
|
Description
|
||
|
|
-----------
|
||
|
|
|
||
|
|
The for command is used to loop over a list of values and execute a series of
|
||
|
|
commands for each of these.
|
||
|
|
|
||
|
|
The counter variable of the loop is a shell variable. Please, keep in mind that
|
||
|
|
an environment variable takes precedence over a shell variable of the same name.
|
||
|
|
|
||
|
|
variable
|
||
|
|
name of the counter variable
|
||
|
|
|
||
|
|
items
|
||
|
|
space separated item list
|
||
|
|
|
||
|
|
commands
|
||
|
|
commands to execute
|
||
|
|
|
||
|
|
Example
|
||
|
|
-------
|
||
|
|
|
||
|
|
::
|
||
|
|
|
||
|
|
=> setenv c
|
||
|
|
=> for c in 1 2 3; do echo item ${c}; done
|
||
|
|
item 1
|
||
|
|
item 2
|
||
|
|
item 3
|
||
|
|
=> echo ${c}
|
||
|
|
3
|
||
|
|
=> setenv c x
|
||
|
|
=> for c in 1 2 3; do echo item ${c}; done
|
||
|
|
item x
|
||
|
|
item x
|
||
|
|
item x
|
||
|
|
=>
|
||
|
|
|
||
|
|
The first line ensures that there is no environment variable *c*. Hence in the
|
||
|
|
first loop the shell variable *c* is printed.
|
||
|
|
|
||
|
|
After defining an environment variable of name *c* it takes precedence over the
|
||
|
|
shell variable and the environment variable is printed.
|
||
|
|
|
||
|
|
Return value
|
||
|
|
------------
|
||
|
|
|
||
|
|
The return value $? after the done statement is the return value of the last
|
||
|
|
statement executed in the loop.
|
||
|
|
|
||
|
|
::
|
||
|
|
|
||
|
|
=> for i in true false; do ${i}; done; echo $?
|
||
|
|
1
|
||
|
|
=> for i in false true; do ${i}; done; echo $?
|
||
|
|
0
|