graham@tcom.stc.co.uk (Graham Bardsley) (10/27/89)
The following shell script is a program that I find very useful for manipulating
compressed tar files. It's an interface to tar which provides the ability to
write compressed files. With it you could write a magtape with for example three
times as much data as you would without this but with no added bother. The script
adds two extra flags to tar and also the ability to tar across a net. The
extra flags are :
d - specify the blocking factor for the dd command within ztar. This is
used to speed up the pipes and for shoving things across the net.
Defaults to 100b (512k).
Z - Create/extract a compressed tar archive. For example, to create a
compressed archive of a subdirectory tree X use :
ztar cfZ X.tar.Z X
ztar has the ability to read/write tars across a net - to use this specify the
filename like <hostname>:/dev/<tape>
I've found ztar very useful (e.g. backing up an entire X11 tree onto one magtape
cartridge or taring to a remote drive)
Have fun
Graham
#! /bin/sh
# ztar : Compress tar shell script - does compression as it writes/reads a tar
# file. Also works across a network!
# Tar flags : ctx befFhilmopvw
#
# additional flags d blocks - blocking factor for dd (default 100 (b))
# Z create/undo a compress file
#
# To access a remote file/device use 'ztar cf hostname:/dev/mt . ' or
# whatever.
#
# G. Bardsley 1989
#
if test "$1" = "" ; then
echo "Usage: ztar {cxt}[flags] file ..." >&2
exit 1
fi
flags=`echo $1 | sed -e 's/./ &/g'`
shift
for flag in $flags ; do
case $flag in
[ctx] )
if test "$op" = "" ; then
op=$flag;
tarflags=${tarflags}${flag}
else
echo "Cant mix $op and ${flag} flags" >&2
exit 1
fi;;
[eFhilmopvw])
tarflags=${tarflags}${flag};;
f )
if test "$device" = "" ; then
if test "$1" = "" ; then
echo "No argument to take -f from" >&2
exit 1
else
device=`echo $1 | sed -e 's/[^:]*:\(.*\)/\1/'`
host=`echo $1 | sed -e 's/\([^:]*\):.*/\1/'`
if test "$device" = "$host" ; then
device=$1
host=
fi
if test "$device" = "" ; then
echo "Null device given in spec $1" >&2
exit 1
fi
if test "$host" != "" ; then
rsh_in_cmd=" rsh $host -n "
rsh_out_cmd=" rsh $host "
fi
shift
fi
else
echo "Already specified device $device" >&2
exit 1
fi;;
b )
if test "$tarblocks" = "" ; then
if test "$1" != "" ; then
tarblocks=$1
shift
tarflags=${tarflags}b
else
echo "No argument to take -b from" >&2
exit 1
fi
else
echo "Already specified -b $tarblocks" >&2
exit 1
fi;;
d )
if test "$ddblocks" = "" ; then
if test "$1" != "" ; then
ddblocks=${1}b
shift
else
echo "No argument to take -d from" >&2
exit 1
fi
else
echo "Already specified -d $ddblocks" >&2
exit 1
fi;;
Z )
compress_cmd="| compress "
uncompress_cmd="| compress -d ";;
* )
echo "Unknown flag $flag" >&2
exit 1;;
esac
done
if test "$op" = "c" ; then
if test "$1" = "" ; then
echo "Usage: ztar {cxt}[flags] file ..." >&2
exit 1
fi
fi
if test "$op" = "" ; then
echo "Usage: ztar {cxt}[flags] file ..." >&2
exit 1
fi
tardirs=$*
if test "$device" = ""; then
device=`printenv | grep "^TAPE" | sed -e 's/TAPE=//'`
fi
if test "$device" = ""; then
echo "No device specified" >&2
exit 1
fi
if test "$host" != "" ; then
PATH=/etc:/usr/etc:$PATH
export PATH
messg=`ping $host`
if test "$?" != "0" ; then
echo $messg | sed -e 's/.*: /ztar: /' >&2
exit 1
fi
fi
if test "$ddblocks" = ""; then
ddblocks=100b
fi
if test "$device" != "-"; then
in_dev="if=${device}"
out_dev="of=${device}"
fi
trap "/bin/rm -f /tmp/zt$$; exit 0" 0 1 2 3 15
case $op in
c )
eval tar ${tarflags}f - $tardirs $compress_cmd | ( $rsh_out_cmd dd ${out_dev} obs=${ddblocks} conv=sync,block 2> /tmp/zt$$) ;;
[xt] )
eval '(' $rsh_in_cmd dd ${in_dev} ibs=${ddblocks} 2> /tmp/zt$$ ')' $uncompress_cmd | tar ${tarflags}Bf - ${tardirs};;
esac
sed -e '/ records /d' /tmp/zt$$ >&2
exit 0
----
Graham Bardsley,STC Telecoms,Oakleigh Road South,New Southgate, London, N11 1HB
...{uunet,mcvax}!ukc!stc!graham <graham@tcom.stc.co.uk> Tel: +44 1 945 2739
--
----
Graham Bardsley,STC Telecoms,Oakleigh Road South,New Southgate, London, N11 1HB
..{uunet,mcvax}!ukc!stc!graham <graham@tcom.stc.co.uk> Tel: +44 1 945 2739