I'm fond of my backup tapes. They have saved the day more than just
once. The problem I have, however, is not in making the backup tapes, but
in keeping track of what's on them and when they were made. I'm sure I'm
not the only systems administrator that has a pile of mystery tapes lying
around. To help me keep that pile manageable, I wrote the MakeIndex script.
The script is a hands-off program. One simply inserts a tape and executes the script. The index is written to standard output. The tape is automatically rewound and ejected when finished.
Dumped from: Wed Feb 17 04:07:04 1999indicates the date of the last lower level dump of /var. For a plethora of information on dump levels, refer to the man pages on ufsdump. You may have noticed that the file systems that had been dumped at level 0 produced the line:
Dumped from: the epochThis indicates that there's no previous lower-level dump for this file system.
Listing A: Standard output from the execution of the MakeIndex shell script
# ./MakeIndex File: 0 Dump date: Thu Feb 18 19:07:03 1999 Dumped from: the epoch Level 0 dump of / on europa:/dev/dsk/c0t3d0s0 File: 1 Dump date: Thu Feb 18 19:18:00 1999 Dumped from: the epoch Level 0 dump of /usr on europa:/dev/dsk/c0t3d0s5 File: 2 Dump date: Thu Feb 18 19:31:23 1999 Dumped from: the epoch Level 0 dump of /export/home on europa:/dev/dsk/c0t3d0s6 File: 3 Dump date: Thu Feb 18 19:51:53 1999 Dumped from: Wed Feb 17 04:07:04 1999 Level 2 dump of /var on europa:/dev/dsk/c0t3d0s7 File: 4 EOM
Listing B: The MakeIndex shell script
1 #!/bin/sh
2 #-------------------------------------------------------------
3 #
4 # MakeIndex: Creates an index for a tape in ufsdump format
5 #
6 #-------------------------------------------------------------
7 TAPE=/dev/rmt/0n
8 ERROR=0
9
10 while [ $ERROR -eq 0 ]
11 do
12 FILENUM='mt -f $TAPE status | grep file | awk '{print $3 }' '
13 echo "\nFile: $FILENUM"
14 echo "quit\c"|ufsrestore -ivf $TAPE 2>/dev/null|grep "ump"
15 # echo "quit\c"|ufsrestore -ivf $TAPE 2>/dev/null|grep "ump "
16 ERROR=$?
17 done
18 echo "EOM"
19 mt $TAPE rewoffl &
20 exit
Typically, the backup consists of a series of dump files. The while loop
will loop over the number of files. For the sake of simplicity, performance,
and flexibility, the script doesn't determine the number of files to loop
over before looping. Rather, the while loop continues as long as the value
of the variable ERROR is zero. You can see in line 12 of Listing B that
the file number of the first record is determined by pruning the file number
from the output of the mt status command. The standard output from the
mt command is piped to grep file and then further reduced by piping to
the awk command. The result, a number indicating the current file position
on the tape is assigned to the variable FILENUM. Line 13 echoes the file
number to standard output.
ufsrestore -ivf $TAPEYou can see that the -ivf parameters are used. The -iv invokes the verbose and interactive modes. The f parameter indicates that we wish to read from the file represented by the variable TAPE. Remember, in UNIX, devices are files. We aren't really interested in using the interactive mode of ufsrestore, though. We use the interactive mode because, when it's invoked, the command generates a description of the dump file, which includes the filesystem that was dumped, the date of the dump, and the dump level. Unfortunately, the command gives us more information than we need, including a prompt for interactive use. Here's what it gives us:
# /usr/sbin/ufsrestore -ivf $TAPE Verify volume and initialize maps Media block size is 126 Dump date: Thur Feb 18 19:18:00 1999 Dumped from: the epoch Level 0 dump of /usr on europa:/dev/ =>dsk/c0t3d0s5 Label: none Extract directories from tape Initialize symbol table. ufsrestore>The ufsrestore command directs the prompt to standard error, which is, by default, represented by file number 2. You can see, in line 14 of Listing B, that the standard error is redirected to suppress the prompt.
ufsrestore -ivf $TAPE 2>/dev/nullTo rid our index of unwanted information produced from the ufsrestore command, we can redirect the standard output to the grep command to pick out only the information of interest. We're interested only in lines that have the string dump in them. These include Dump, Dumped, and dump. We pipe the output to grep and search for these strings. We need to restrict our search string to pick out the string ump:
ufsrestore -ivf $TAPE 2>/dev/ =>null | grep "ump"Since we invoked the interactive mode, we need to enter the quit command to ufsrestore's standard input. We can again use a pipe to redirect the output of the echo to the input of ufsrestore:
echo "quit\c"|ufsrestore -ivf $TAPE 2>/ =>dev/null|grep "ump"
Since I almost always perform level 0 dumps, I got tired of seeing the line
Dumped from: the epochIf you're not interested in the dump level, or if you just don't like seeing the facetious reference to the epoch, you can comment out line 14 in Listing B and uncomment line 15. The difference between these lines is simply a space at the end of the string ump. The space eliminates the occurrence of the string containing Dumped in the MakeIndex output.