Re: more fun with parameter expansion

[Peter Stephenson <pws@cambridgesiliconradio.com>]

I wrote:
> Clint Adams wrote:
> > This is for someone who wants to take a directory tree and convert all
> > the filenames (and directory names) to lowercase, replacing spaces
> > with underscores.
> 
> See zmv in the Functions/Misc directory of 3.1.9 (this version is needed
> for it to work).
> 
> zmv '(**/)(*[ A-Z]*)' '${1}${(L)2/ /_}'
> 
> works on a simple test case (use the option -n just to test what it would
> do).

However, it didn't do depth-first matching, so things like `MYDIR/MYFILE'
were screwed up because it tried to rename MYDIR to mydir, then
MYDIR/MYFILE (which didn't exist) to MYDIR/myfile.

Luckily, there are now glob qualifiers to do depth-first ordering: **/*(odon)
orders first by depth under a given directory, then by name.

> Looks
> like zmv needs the option to ignore files whose names didn't change (it's a
> pain having to make the LH pattern so specific).

I've made this the default.  I can't see why you would want the error.

Now you should be able to do

  zmv '(**/)(*)' '${1}${(L)2// /_}'

(I should have put the doubled slash in last time).

I'm sending this to zsh-users, because you can always copy an installed zmv
and patch it yourself.

Index: Functions/Misc/zmv
===================================================================
RCS file: /cvsroot/zsh/zsh/Functions/Misc/zmv,v
retrieving revision 1.2
diff -u -r1.2 zmv
--- Functions/Misc/zmv	2000/05/05 14:14:12	1.2
+++ Functions/Misc/zmv	2000/06/19 09:02:41
@@ -61,10 +61,11 @@
 # other words, parenthesising of wildcards is independent of any existing
 # parentheses.
 #
-# Any error --- a substitution resulted in an empty string, a
-# substitution did not change the file name, two substitutions gave the
-# same result, the destination was an existing regular file and -f was not
-# given --- causes the entire function to abort without doing anything.
+# Any file whose name is not changed by the substitution is simply ignored.
+# Any error --- a substitution resulted in an empty string, two
+# substitutions gave the same result, the destination was an existing
+# regular file and -f was not given --- causes the entire function to abort
+# without doing anything.
 #
 # Options:
 #  -f  force overwriting of destination files.  Not currently passed
@@ -76,7 +77,8 @@
 #  -n  no execution: print what would happen, but don't do it.
 #  -q  Turn bare glob qualifiers off:  now assumed by default, so this
 #      has no effect.
-#  -Q  Force bare glob qualifiers on.
+#  -Q  Force bare glob qualifiers on.  Don't turn this on unless you are
+#      actually using glob qualifiers in a pattern (see below).
 #  -s  symbolic, passed down to ln; only works with zln or z?? -L.
 #  -v  verbose: print line as it's being executed.
 #  -o <optstring>
@@ -119,7 +121,7 @@
 local f g args match mbegin mend files action myname tmpf opt exec
 local opt_f opt_i opt_n opt_q opt_Q opt_s opt_M opt_C opt_L 
 local opt_o opt_p opt_v opt_w MATCH MBEGIN MEND
-local pat repl errstr fpat
+local pat repl errstr fpat hasglobqual opat
 typeset -A from to
 integer stat
 
@@ -190,17 +192,29 @@
   fi
 fi
 
+if [[ -n $opt_Q && $pat = (#b)(*)\([^\)\|\~]##\) ]]; then
+  hasglobqual=q
+  # strip off qualifiers for use as ordinary pattern
+  opat=$match[1]
+fi
+
 if [[ $pat = (#b)(*)\((\*\*##/)\)(*) ]]; then
   fpat="$match[1]$match[2]$match[3]"
+  # Now make sure we do depth-first searching.
+  # This is so that the names of any files are altered before the
+  # names of the directories they are in.
+  if [[ -n $opt_Q && -n $hasglobqual ]]; then
+    fpat[-1]="odon)"
+  else
+    setopt bareglobqual
+    fpat="${fpat}(odon)"
+  fi
 else
   fpat=$pat
 fi
 files=(${~fpat})
 
-if [[ -o bareglobqual && $pat = (#b)(*)\([^\)\|\~]##\) ]]; then
-  # strip off qualifiers for use as ordinary pattern
-  pat=$match[1]
-fi
+[[ -n $hasglobqual ]] && pat=$opat
 
 errs=()
 
@@ -219,7 +233,9 @@
   if [[ -z $g ]]; then
     errs=($errs "$f expanded to empty string")
   elif [[ $f = $g ]]; then
-    errs=($errs "$f not altered by substitution")
+    # don't cause error: more useful just to skip
+    #   errs=($errs "$f not altered by substitution")
+    continue
   elif [[ -n $from[$g] && ! -d $g ]]; then
     errs=($errs "$f and $from[$g] both map to $g")
   elif [[ -f $g && -z $opt_f ]]; then

-- 
Peter Stephenson <pws@cambridgesiliconradio.com>
Cambridge Silicon Radio, Unit 300, Science Park, Milton Road,
Cambridge, CB4 0XL, UK                          Tel: +44 (0)1223 392070