34e452dd02
Currently all shell command docs are put in the doc/usage root. Let's group them into cmd/ sub-directory. Signed-off-by: Bin Meng <bmeng.cn@gmail.com> Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
66 lines
1.2 KiB
ReStructuredText
66 lines
1.2 KiB
ReStructuredText
for command
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===========
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Synopis
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-------
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::
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for <variable> in <items>; do <commands>; done
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Description
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-----------
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The for command is used to loop over a list of values and execute a series of
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commands for each of these.
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The counter variable of the loop is a shell variable. Please, keep in mind that
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an environment variable takes precedence over a shell variable of the same name.
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variable
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name of the counter variable
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items
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space separated item list
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commands
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commands to execute
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Example
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-------
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::
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=> setenv c
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=> for c in 1 2 3; do echo item ${c}; done
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item 1
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item 2
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item 3
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=> echo ${c}
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3
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=> setenv c x
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=> for c in 1 2 3; do echo item ${c}; done
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item x
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item x
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item x
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=>
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The first line ensures that there is no environment variable *c*. Hence in the
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first loop the shell variable *c* is printed.
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After defining an environment variable of name *c* it takes precedence over the
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shell variable and the environment variable is printed.
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Return value
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------------
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The return value $? after the done statement is the return value of the last
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statement executed in the loop.
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::
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=> for i in true false; do ${i}; done; echo $?
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1
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=> for i in false true; do ${i}; done; echo $?
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0
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