Ports tree depencency calculation

The first run scans the whole ports tree:

 export PORTSDIR=/path/to/ports
 export DEPENDSDIR=/var/db/chkversion
 mkdir -p $DEPENDSDIR
 depends.pl

On the following runs, a file containing updated files is created:
 CVSOUT=`mktemp`; CVSERR=`mktemp`    
 cd $PORTSDIR && cvs -R -q update -AdP >"$CVSOUT" 2>"$CVSERR"           

 export FILESLIST=`mktemp` 
 sed -n -e 's/^[UPM] //p' "$CVSOUT" >"$FILESLIST"
 sed -n -e 's/^cvs update: \(.*\)is no longer in the repository$/\1/p' "$CVSERR" >>"$FILESLIST"
 rm "$CVSOUT" "$CVSERR"

and fed in the script like above

 export PORTSDIR=/path/to/ports
 export DEPENDSDIR=/var/db/chkversion
 mkdir -p $DEPENDSDIR
 export PORTSLIST=$DEPENDSDIR/PORTSLIST
 depends.pl
 rm $FILESLIST

now $PORTSLIST contains a list of affected ports.


EXAMPLES:

print all slave ports of mail/exim:

awk -F\| '$1 == "mail/exim/Makefile" {print $3}' $DEPENDSDIR/DEPENDS


NOTES:

When not all modified files are fed into the script, the database gets
out of sync and has to be regenerated.