slootman@dri.nl (Paul Slootman) (04/16/91)
Hi,
I've just come across a detail of (Bourne) shell programming that I've
not seen before. If a script has more than 9 positional parameters,
there seems to be no way to *directly* access the tenth onwards. Try
this:
$ set a b c d e f g h i j k l m n o p
$ echo $9
i
$ echo $10
a0
$ echo ${10}
sh: bad substitution
Is this a "feature"? The ksh does it ok, but that's not an option for
all the systems we have here. We've done a workaround by assigning to
other variables and shifting, but I was wondering if there isn't any
other way. Nothing in TFM states anything about problems with more
than 9 parameters (unless I've overlooked it...)
FYI, it's on System V systems.
Paul.
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=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=omerzu@quando.quantum.de (Thomas Omerzu) (04/16/91)
In article <991@dri500.dri.nl> slootman@dri.nl (Paul Slootman) writes: [...] >not seen before. If a script has more than 9 positional parameters, >there seems to be no way to *directly* access the tenth onwards. Try [...] >other way. Nothing in TFM states anything about problems with more >than 9 parameters (unless I've overlooked it...) Quote from sh(1): Parameter Substitution The character $ is used to introduce substitutable parameters. There are two types of parameters, positional and keyword. If parameter is a digit, it is a positional . ^^^^^ parameter. Positional parameters may be assigned values by set. Keyword parameters (also known as variables) may be assigned values by writing: digit != number :-) -- *--------------------------------------------------------------------------* Thomas Omerzu. Internet: omerzu@quantum.de Quantum GmbH Bitnet: omerzu%quando@UNIDO.bitnet Dortmund,Germany UUCP: ...!unido!quando!omerzu
slootman@dri.nl (Paul Slootman) (04/16/91)
In article <1998@quando.quantum.de> omerzu@quantum.de (Thomas Omerzu) writes: |>not seen before. If a script has more than 9 positional parameters, |>there seems to be no way to *directly* access the tenth onwards. Try |[...] |>other way. Nothing in TFM states anything about problems with more |>than 9 parameters (unless I've overlooked it...) | |Quote from sh(1): | | Parameter Substitution | The character $ is used to introduce substitutable | parameters. There are two types of parameters, positional | and keyword. If parameter is a digit, it is a positional |. ^^^^^ | parameter. Positional parameters may be assigned values by [...] |digit != number :-) OOPS! You're right... OK, so, there *ISN'T* a way to directly access positional parameters beyond $9 (besides shifting). :-( I'll stay with my hack, then. Paul. -- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= : slootman@dri.nl : You are wise, witty and wonderful, but you : : ...!hp4nl!dri500!slootman : spend too much time reading this sort of trash. : =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
rhartman@thestepchild.sgi.com (Robert Hartman) (04/17/91)
In article <1998@quando.quantum.de> omerzu@quantum.de (Thomas Omerzu) writes: > >In article <991@dri500.dri.nl> slootman@dri.nl (Paul Slootman) writes: > >[...] >>not seen before. If a script has more than 9 positional parameters, >>there seems to be no way to *directly* access the tenth onwards. Try >[...] >>other way. Nothing in TFM states anything about problems with more >>than 9 parameters (unless I've overlooked it...) > >Quote from sh(1): > > Parameter Substitution > The character $ is used to introduce substitutable > parameters. There are two types of parameters, positional > and keyword. If parameter is a digit, it is a positional >. ^^^^^ > parameter. Positional parameters may be assigned values by > set. Keyword parameters (also known as variables) may be > assigned values by writing: > > >digit != number :-) There isn't any way to do that directly. However, I've never encounterd a case where I wanted to get at $10 without also wanting to (or being willing to) get at $1-$9. Here's an example of how I get at each argument in turn: while [ $# -gt 0 ] ; do case $1 in -*) options="$options $1" ;; *) files="$files $1" ;; esac shift done I suppose you could combine this with some sort of test to get at $10: tmp="$@" #capture args list in temp variable while [ $# -gt 0 ] ; do if [ `expr $# - 10` -eq 0 ] ; then arg10="$1" ; fi shift done set $tmp #restore original args list Or you could use your favorite counting look and stick a shift command in there. But for handling a variable argument list, I like the first option best. -r
greg@cheers.Bungi.COM (Greg Onufer) (04/17/91)
slootman@dri.nl (Paul Slootman) writes: >OK, so, there *ISN'T* a way to directly access positional parameters >beyond $9 (besides shifting). :-( I'll stay with my hack, then. Please note that (at least in the draft I have) POSIX specifies in its Shells and Utilities standard that ${10} and higher are allowed and work as expected. The braces are required, but are optional in the single digit case (so scripts that relied on $10 being ${1}0 still work?). Conclusion? Get yourself a POSIX-compliant shell. Cheers!greg