Very Computer

by **William Par** » Thu, 10 Jun 2004 15:26:09

I'm trying to run 'cat *.x' only if *.x files exist. What is the
cleanest way of doing this? I'm doing it by
shopt -s nullglob
for i in *.x; do cat $i; done
but this is aweful typing.

--

No, I will not fix your computer! I'll reformat your harddisk, though.

by **Chris F.A. Johnso** » Thu, 10 Jun 2004 15:39:28

Quote:> I'm trying to run 'cat *.x' only if *.x files exist. What is the
> cleanest way of doing this? I'm doing it by
> shopt -s nullglob
> for i in *.x; do cat $i; done
> but this is aweful typing.

set -- *.x
[ -f "$1" ] && cat -- *.x

--
Chris F.A. Johnson http://cfaj.freeshell.org/shell
===================================================================
My code (if any) in this post is copyright 2004, Chris F.A. Johnson
and may be copied under the terms of the GNU General Public License

by **Stephane CHAZELA** » Thu, 10 Jun 2004 18:46:25

2004-06-9, 06:26(+00), William Park:

Quote:> I'm trying to run 'cat *.x' only if *.x files exist. What is the
> cleanest way of doing this? I'm doing it by
> shopt -s nullglob
> for i in *.x; do cat $i; done
> but this is aweful typing.

zsh -c 'cat ./*.x'

With bash:

shopt -s nullglob
files=(./*.x)

else
printf >&2 '%s\n' "${0##*/}: no *.x files"
false
fi

You could also do:

cat /dev/null ./*.x

--
Stephane

by **Bill Marcu** » Thu, 10 Jun 2004 23:09:40

On 9 Jun 2004 06:26:09 GMT, William Park

> I'm trying to run 'cat *.x' only if *.x files exist. What is the
> cleanest way of doing this? I'm doing it by
> shopt -s nullglob
> for i in *.x; do cat $i; done
> but this is aweful typing.

cat *.x 2>/dev/null
will cat the files without producing a "No such file" error message, but
it will also ignore other errors.

--
Simulations are like miniskirts, they show a lot and hide the essentials.
-- Hubert Kirrman

by **rakesh shar** » Fri, 11 Jun 2004 00:15:34

> I'm trying to run 'cat *.x' only if *.x files exist. What is the
> cleanest way of doing this? I'm doing it by
> shopt -s nullglob
> for i in *.x; do cat $i; done
> but this is aweful typing.

set -- [*].x *.x
case $1$2 in
'[*.x]*.x'):;;
*) shift
for i
do
[ -f "$i" ] && cat "$i";;
done
esac

by **Stephane CHAZELA** » Fri, 11 Jun 2004 01:27:03

2004-06-9, 08:15(-07), rakesh sharma:
[...]

Quote:> set -- [*].x *.x
> case $1$2 in
> '[*.x]*.x'):;;

'[*].x*.x') ;;

Quote:> *) shift
> for i
> do
> [ -f "$i" ] && cat "$i";;

cat -- "$i";;

Quote:> done
> esac

or use ./*.x

--
Stephane

by **William Par** » Fri, 11 Jun 2004 04:10:11

> 2004-06-9, 06:26(+00), William Park:
> > I'm trying to run 'cat *.x' only if *.x files exist. What is the
> > cleanest way of doing this? I'm doing it by
> > shopt -s nullglob
> > for i in *.x; do cat $i; done
> > but this is aweful typing.
> cat /dev/null ./*.x

Nice! Thanks Stephane.

--

No, I will not fix your computer! I'll reformat your harddisk, though.

by **Chris F.A. Johnso** » Fri, 11 Jun 2004 13:35:55

>> 2004-06-9, 06:26(+00), William Park:
>> > I'm trying to run 'cat *.x' only if *.x files exist. What is the
>> > cleanest way of doing this? I'm doing it by
>> > shopt -s nullglob
>> > for i in *.x; do cat $i; done
>> > but this is aweful typing.

>> cat /dev/null ./*.x

> Nice! Thanks Stephane.

$ cat /dev/null ./*.x
cat: ./*.x: No such file or directory

--
Chris F.A. Johnson http://cfaj.freeshell.org/shell
===================================================================
My code (if any) in this post is copyright 2004, Chris F.A. Johnson
and may be copied under the terms of the GNU General Public License

by **William Par** » Fri, 11 Jun 2004 14:44:47

> >> 2004-06-9, 06:26(+00), William Park:
> >> > I'm trying to run 'cat *.x' only if *.x files exist. What is the
> >> > cleanest way of doing this? I'm doing it by
> >> > shopt -s nullglob
> >> > for i in *.x; do cat $i; done
> >> > but this is aweful typing.

> >> cat /dev/null ./*.x

> > Nice! Thanks Stephane.

> $ cat /dev/null ./*.x
> cat: ./*.x: No such file or directory

With 'shopt' of course. :-)

--

No, I will not fix your computer! I'll reformat your harddisk, though.

by **rakesh shar** » Fri, 11 Jun 2004 21:49:47

> 2004-06-9, 06:26(+00), William Park:
> > I'm trying to run 'cat *.x' only if *.x files exist. What is the
> > cleanest way of doing this? I'm doing it by
> > shopt -s nullglob
> > for i in *.x; do cat $i; done
> > but this is aweful typing.

...[snipped].....

Quote:> You could also do:

> cat /dev/null ./*.x

hi Stephane

Can you explain the rationale for the above? If some dir. ends in .x how
would it handle that? what is the function of /dev/null?

---
Rakesh.

by **Stephane CHAZELA** » Fri, 11 Jun 2004 23:10:45

2004-06-10, 05:49(-07), rakesh sharma:
[...]

Quote:>> > shopt -s nullglob
[...]
>> You could also do:

>> cat /dev/null ./*.x

> hi Stephane

> Can you explain the rationale for the above? If some dir. ends in .x how
> would it handle that? what is the function of /dev/null?

The above supposed the nullglob bash option was on.

This way, if there's no .x file, the command resolves to
cat /dev/null
that does nothing.

Without the /dev/null, it would resolve to:
cat
that reads stdin.

Sorry, my post was not clear.

--
Stephane

Very Computer

'cat file' but only if 'file' exist

'cat file' but only if 'file' exist

'cat file' but only if 'file' exist

'cat file' but only if 'file' exist

'cat file' but only if 'file' exist

'cat file' but only if 'file' exist

'cat file' but only if 'file' exist

'cat file' but only if 'file' exist

'cat file' but only if 'file' exist

'cat file' but only if 'file' exist

'cat file' but only if 'file' exist

'cat file' but only if 'file' exist