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Regnecentalen RC-900

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⟦53009e89a⟧ TextFile

    Length: 1900 (0x76c)
    Types: TextFile
    Notes: UNIX file
    Names: »lockfilter«

Derivation

└─⟦c93a30372⟧ Bits:30004169/disk3.imd Uniplex II+ V.6 release 1.0 (dansk)
└─⟦c93a30372⟧ UNIX Filesystem
    └─⟦this⟧ »up/new/usr/UAP/unsupported/lockfilter«

TextFile


: '
lockfilter - noddy locking filter
             (for spooler-less systems)
'
USAGE='
Usage: lockfilter [-V] [-addcr] [-bg] [lockname]

   lockname    arbitrary name. Defaults to "lockprint"
       -addcr  adds CR before every LF
       -bg     Background: No interactive control of locks

Standard UNIX filter mechanisms. eg:

uprint -p file | lockfilter >/dev/tty12
'

: Argument scan/default

ADDCR=
BG=
for ARG do
   case "$ARG" in
      -[Vv] ) echo "$0: Vs. AP.03" >&2; exit 1;;
      -addcr) ADDCR=YES;;
      -bg   ) BG=YES;;
           *) case "$LOCKNAME" in
               '') LOCKNAME="$ARG";;
                *) echo "Unexpected argument: \"$ARG\"$USAGE" >&2
                   exit 1;;
               esac
               ;;
   esac
done
LOCKNAME=${LOCKNAME-lockprint}

: Work in lock direcory

LOCKDIR=/tmp/.Ulocks
if ( cd $LOCKDIR ) >/dev/null 2>&1; then
   cd $LOCKDIR
else
   mkdir $LOCKDIR >/dev/null 2>&1
   cd $LOCKDIR || 
   {  echo "$0: Can't create/enter $LOCKDIR" >&2
      exit 1
   }
   chmod 777 $LOCKDIR
fi

: Hold on lock. User interaction must be on stderr

if test -f "$LOCKNAME"; then
   case "$BG" in
   YES) echo "
Device is locked (LOCKNAME=$LOCKNAME). Please retry later" >&2
        exit 1;;
   esac

(  STILL=
   while test -f "$LOCKNAME"; do
      echo "
Device is$STILL locked (LOCKNAME=$LOCKNAME). Options available:

1 - Try to proceed (eg: someone else has freed the lock now)
2 - Abort operation
3 - Remove the lock

Please enter choice number follwed by <RETURN>
(or just <RETURN> for choice 1)"
      STILL=" still"
      read RSP SCRAP
      case "$RSP" in
      ''|1) ;;
         2) exit 1;;
         3) rm -f "$LOCKNAME";;
         *) echo "Invalid response, \"$RSP\"";;
      esac
   done
   exit 0
) <&2 >&2 || exit
fi

>"$LOCKNAME"

case "$ADDCR" in
YES) CR=`echo | tr '\012' '\015'`
     sed "s/$/$CR/"
     ;;
  *) cat;;
esac
rm -f "$LOCKNAME"