[email protected] a écrit :
AST-Users,
I had written a function essentially like "loadTheArrayVer2" below. In
the calling code, after calling the function, my array was dead empty.
To my way of thinking, this behavior is most unexpected, If this is
proper, then please help me understand the logic behind it, so that I
don't make the same mistake again.
$ cat kshScopeIssue
function loadTheArrayVer1
{
nameref array_ref=$1
print | for i in justOnce; do array_ref[jdoe]='John Doe'; done
}
function loadTheArrayVer2
{
nameref array_ref=$1
print | for i in justOnce; do array_ref[jdoe]='John Doe'; done |
while read; do :; done
}
function loadTheArrayVer3
{
nameref array_ref=$1
for i in justOnce; do array_ref[jdoe]='John Doe'; done | while read;
do :; done
}
<snip>
$ ./kshScopeIssue
Version JM 93t+ 2010-02-02
Using loadTheArrayVer1: John Doe
Using loadTheArrayVer2:
Using loadTheArrayVer3:
only the last sequence of a pipe may be executed in the current shell,
the others sequences are executed in a subshell, so variable assignments
are lost in there.
the portable way to keep assignments w/in loop is as follow :
function loadTheArrayVer0
{
nameref array_ref=$1
for i in justOnce; do array_ref[jdoe]='John Doe'; done << EOF
$(print)
EOF
}
man /opt/ast/man/man1/sh.1
A pipeline is a sequence of one or more commands separated by |. The
standard output of each command but the last is connected by a pipe(2)
to the standard input of the next command. Each command, except possi-
bly the last, is run as a separate process; the shell waits for the
last command to terminate. The exit status of a pipeline is the exit
status of the last command unless the pipefail option is enabled. Each
pipeline can be preceded by the reserved word ! which causes the exit
status of the pipeline to become 0 if the exit status of the last com-
mand is non-zero, and 1 if the exit status of the last command is 0.
take care, in bash or pdksh, all sequences of a pipe are executed in a
subshell !
man bash
Each command in a pipeline is executed as a separate process (i.e., in
a subshell).
ksh88
$ ^Version 11/16/88f
$ i=1 | j=1
$ echo $i:$j
:1
ksh93
$ echo ${.sh.version}
Version JM 93t+ 2009-05-01
ditto
bash
$ echo $BASH_VERSION
3.2.49(23)-release
$ i=1 | j=1
$ echo $i:$j
:
pdksh
$ echo $KSH_VERSION
@(#)PD KSH v5.2.14 99/07/13.2
ditto
Regards,
Cyrille Lefevre
--
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