* Test if parameter is set
@ 2011-04-19 16:48 Thorsten Kampe
2011-04-19 17:19 ` Frank Terbeck
` (2 more replies)
0 siblings, 3 replies; 5+ messages in thread
From: Thorsten Kampe @ 2011-04-19 16:48 UTC (permalink / raw)
To: zsh-users
Hi,
how can I test if a parameter is set?
Like in...
if $VAR_IS_SET; then
print Variable is set
else
print Variable is not set
fi
Thorsten
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Test if parameter is set
2011-04-19 16:48 Test if parameter is set Thorsten Kampe
@ 2011-04-19 17:19 ` Frank Terbeck
2011-04-19 17:22 ` Stephane Chazelas
2011-04-19 17:26 ` Peter Stephenson
2 siblings, 0 replies; 5+ messages in thread
From: Frank Terbeck @ 2011-04-19 17:19 UTC (permalink / raw)
To: Thorsten Kampe; +Cc: zsh-users
Thorsten Kampe wrote:
> how can I test if a parameter is set?
>
> Like in...
>
> if $VAR_IS_SET; then
> print Variable is set
> else
> print Variable is not set
> fi
In zsh:
if (( ${+parameters[foo]} )); then
: set
else
: unset
fi
In POSIX shells:
if [ x${foo+set} = xset ]; then
: set
else
: unset
fi
Regards, Frank
--
In protocol design, perfection has been reached not when there is
nothing left to add, but when there is nothing left to take away.
-- RFC 1925
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Test if parameter is set
2011-04-19 16:48 Test if parameter is set Thorsten Kampe
2011-04-19 17:19 ` Frank Terbeck
@ 2011-04-19 17:22 ` Stephane Chazelas
2011-04-19 17:26 ` Peter Stephenson
2 siblings, 0 replies; 5+ messages in thread
From: Stephane Chazelas @ 2011-04-19 17:22 UTC (permalink / raw)
To: Thorsten Kampe; +Cc: zsh-users
2011-04-19 18:48:57 +0200, Thorsten Kampe:
> Hi,
>
> how can I test if a parameter is set?
>
> Like in...
>
> if $VAR_IS_SET; then
> print Variable is set
> else
> print Variable is not set
> fi
[...]
if (($+VAR))
or portably:
if [ -n "${VAR+x}" ]
--
Stephane
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Test if parameter is set
2011-04-19 16:48 Test if parameter is set Thorsten Kampe
2011-04-19 17:19 ` Frank Terbeck
2011-04-19 17:22 ` Stephane Chazelas
@ 2011-04-19 17:26 ` Peter Stephenson
2011-04-19 17:32 ` Peter Stephenson
2 siblings, 1 reply; 5+ messages in thread
From: Peter Stephenson @ 2011-04-19 17:26 UTC (permalink / raw)
To: zsh-users
On Tue, 19 Apr 2011 18:48:57 +0200
Thorsten Kampe <thorsten@thorstenkampe.de> wrote:
> how can I test if a parameter is set?
if (( ${+VAR} )); then
...
is the zsh-specific answer. However, you can do this in a more standard
way, should you wish, with
if [[ -n ${VAR+1} ]]; then
...
(note no ":").
--
Peter Stephenson <pws@csr.com> Software Engineer
Tel: +44 (0)1223 692070 Cambridge Silicon Radio Limited
Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, UK
Member of the CSR plc group of companies. CSR plc registered in England and Wales, registered number 4187346, registered office Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, United Kingdom
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Test if parameter is set
2011-04-19 17:26 ` Peter Stephenson
@ 2011-04-19 17:32 ` Peter Stephenson
0 siblings, 0 replies; 5+ messages in thread
From: Peter Stephenson @ 2011-04-19 17:32 UTC (permalink / raw)
To: zsh-users
On Tue, 19 Apr 2011 18:26:41 +0100
Peter Stephenson <Peter.Stephenson@csr.com> wrote:
> However, you can do this in a more standard way, should you wish,
> with
>
> if [[ -n ${VAR+1} ]]; then
> ...
(Not yet *that* standard, in fact, but Frank has covered that.)
--
Peter Stephenson <pws@csr.com> Software Engineer
Tel: +44 (0)1223 692070 Cambridge Silicon Radio
Limited Churchill House, Cambridge Business Park, Cowley Road,
Cambridge, CB4 0WZ, UK
Member of the CSR plc group of companies. CSR plc registered in England and Wales, registered number 4187346, registered office Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, United Kingdom
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2011-04-19 17:32 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2011-04-19 16:48 Test if parameter is set Thorsten Kampe
2011-04-19 17:19 ` Frank Terbeck
2011-04-19 17:22 ` Stephane Chazelas
2011-04-19 17:26 ` Peter Stephenson
2011-04-19 17:32 ` Peter Stephenson
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