maart@cs.vu.nl (Maarten Litmaath) (03/23/89)
leo@philmds.UUCP (Leo de Wit) writes:
\set - $pattern # expand into $*
\case $# in
\1) p1="$1" # one arg only; could be mismatch.
\ set - $pattern?* # retry with other pattern (one char extra).
\ n2=$# # save number of matches.
\ set - $pattern* # retry with yet another pattern.
\ case $# in # 1 <= $n2 <= $# holds now.
\ 1) case $1 in
\ "$p1") : ;; # valid match on $p1.
^^^^^^^^^^^
not always (see below)
\ *) shift;; # no match; empty $*.
\ esac;;
\ $n2) set ""; shift;; # matches for $pattern* == # matches for $pattern?*,
\ # so no match on $p1; empty $*.
\ *) set "$p1";; # $# > n2 so there was a valid match on $p1.
\ esac;;
\esac
That can be done far more easier!
set - $pattern
case $# in
1)
case $pattern in
$1)
shift # neglect pathological file names like *[QZ]
esac
esac
Notice the trick: normally $pattern won't match $1 -
"bin" matches "b??", but "b??" doesn't match "bin"
Shortcomings: Leo's script will incorrectly let "*[QZ]" match itself,
my script won't let * match itself.
I guess one needs at least 1 invocation of `test'.
The `shift' statement should be replaced with:
case $1 in
*[[?*]*)
[ -f $1 -o -d $1 ] || shift
;;
*)
shift
esac
If `patterns' without special characters are allowed, simply:
[ -f $1 -o -d $1 ] || shift
--
Modeless editors and strong typing: |Maarten Litmaath @ VU Amsterdam:
both for people with weak memories. |maart@cs.vu.nl, mcvax!botter!maartleo@philmds.UUCP (Leo de Wit) (03/25/89)
In article <2206@solo2.cs.vu.nl> maart@cs.vu.nl (Maarten Litmaath) writes: |leo@philmds.UUCP (Leo de Wit) writes: [my shell script] |That can be done far more easier! | | set - $pattern | | case $# in | 1) | case $pattern in | $1) | shift # neglect pathological file names like *[QZ] | esac | esac | |Notice the trick: normally $pattern won't match $1 - | | "bin" matches "b??", but "b??" doesn't match "bin" But this fails to recognize patterns without meta-characters. For instance: if you have a file named foo, and pattern=foo. My method _does_ recognize that, and correctly decides whether the file exists. |Shortcomings: Leo's script will incorrectly let "*[QZ]" match itself, That is correct; I overlooked the fact that one can construct a filename that will not match itself as a wildcard expression. It has to be pretty weird, though (all wildcard expressions consisting of normal characters, * and ? always match themselves as filenames, if I'm not mistaken, so it has to contain a [...] range expression. Even this can probably be handled if one tries hard enough). |my script won't let * match itself. |I guess one needs at least 1 invocation of `test'. If test is not a builtin, I'd probably go for the ls -d $pattern 2>/dev/null method; it is shorter, clearer and probably just as fast. Leo.