1 #!/bin/bash 2 # ==> Script by James R. Van Zandt, and used here with his permission. 3 4 # ==> Comments added by author of this document. 5 6 7 HERE=`uname -n` # ==> hostname 8 THERE=bilbo 9 echo "starting remote backup to $THERE at `date +%r`" 10 # ==> `date +%r` returns time in 12-hour format, i.e. "08:08:34 PM". 11 12 # make sure /pipe really is a pipe and not a plain file 13 rm -rf /pipe 14 mkfifo /pipe # ==> Create a "named pipe", named "/pipe". 15 16 # ==> 'su xyz' runs commands as user "xyz". 17 # ==> 'ssh' invokes secure shell (remote login client). 18 su xyz -c "ssh $THERE \"cat >/home/xyz/backup/${HERE}-daily.tar.gz\" < /pipe"& 19 cd / 20 tar -czf - bin boot dev etc home info lib man root sbin share usr var >/pipe 21 # ==> Uses named pipe, /pipe, to communicate between processes: 22 # ==> 'tar/gzip' writes to /pipe and 'ssh' reads from /pipe. 23 24 # ==> The end result is this backs up the main directories, from / on down. 25 26 # ==> What are the advantages of a "named pipe" in this situation, 27 # ==>+ as opposed to an "anonymous pipe", with |? 28 # ==> Will an anonymous pipe even work here? 29 30 31 exit 0 |
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