gph@hpsemc.HP.COM (Paul Houtz) (06/06/89)
In my ksh, the "set" command doesn't seem to work within a function:
As a shell command I do the following:
$ set `date`
$ echo $4
16:31:00
Now if I declare a function:
$ foo () {
/ set `date`
/ }
$ foo
$ echo $4
16:31:00
As you can see, the old `date` is still in the positional parameters, otherwise
the seconds part of the date should have changed by now.
Is this a bug in ksh? Is it a feature? Is there some explanation of this
feature?
Thanks for any help you can give.
Paul Houtz
HP Technology Access Center
10670 N. Tantau Avenue
Cupertino, Ca 95014
(408) 725-3864
hplabs!hpda!hpsemc!gph
gph%hpsemc@hplabs.HP.COM
lml@cbnews.ATT.COM (L. Mark Larsen) (06/07/89)
# In article <570024@hpsemc.HP.COM> gph@hpsemc.HP.COM (Paul Houtz) writes:
#
# In my ksh, the "set" command doesn't seem to work within a function:
#
It works in a function - it just sets the positional parameters for
*that* function - not the current shell.
# As a shell command I do the following:
(example deleted)
#
# Is this a bug in ksh? Is it a feature? Is there some explanation of this
# feature?
This is not a bug but the way functions are supposed to work. To modify
the positional parameters of the current shell by executing some shell
script, use ". filename [args]" (reads the file and executes it in the
current environment). Note that Bourne shell does not allow arguments
and that in ksh, passing arguments in this manner is the same as setting
the positional parameters of the current shell.
cheers,
-lmlvinoski@apollo.COM (Stephen Vinoski) (06/08/89)
In article <570024@hpsemc.HP.COM> gph@hpsemc.HP.COM (Paul Houtz) writes: > >In my ksh, the "set" command doesn't seem to work within a function: > > $ set `date` > $ echo $4 > 16:31:00 > >Now if I declare a function: > > $ foo () { > / set `date` > / } > > $ foo > $ echo $4 > 16:31:00 > >As you can see, the old `date` is still in the positional parameters, otherwise >the seconds part of the date should have changed by now. In ksh, positional parameters are not shared between the function and its caller. Try "The Kornshell Command and Programming Language", Morris I. Bolsky and David G. Korn, Prentice-Hall, 1989, ISBN 0-13-516972-0. It's a great book. -steve -- Steve Vinoski ## Apollo, a Subsidiary of HP ## ARPA: vinoski@apollo.com (508)256-6600 x5904 ## Chelmsford, MA 01824 ## UUCP: ...!apollo!vinoski "...no hardware designer should be allowed to produce any piece of hardware until 3 software guys have signed off for it." -Andy Tanenbaum
allbery@ncoast.ORG (Brandon S. Allbery) (06/11/89)
As quoted from <570024@hpsemc.HP.COM> by gph@hpsemc.HP.COM (Paul Houtz): +--------------- | In my ksh, the "set" command doesn't seem to work within a function: | Is this a bug in ksh? Is it a feature? Is there some explanation of this | feature? +--------------- Feature. Positional parameters are local to a function; as "set" sets positional parameters, its effect is lost when the function exits. Under (System V) /bin/sh, positionals are global: "set" works the way you expect, but calling a function with arguments destroys the shell's global parameters -- which has caused me considerable annoyance at times. I prefer the ksh implementation. ++Brandon -- Brandon S. Allbery, moderator of comp.sources.misc allbery@ncoast.org uunet!hal.cwru.edu!ncoast!allbery ncoast!allbery@hal.cwru.edu Send comp.sources.misc submissions to comp-sources-misc@<backbone> NCoast Public Access UN*X - (216) 781-6201, 300/1200/2400 baud, login: makeuser