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Top Forums UNIX for Dummies Questions & Answers Subtracting Variables which are commands Post 1771 by PxT on Thursday 29th of March 2001 10:55:10 AM
Old 03-29-2001
This gets tricky because what if their login time is 2:59, and the logout time is 3:10. 3:10-2:59=? The shell doesn't know that you are trying to subtract times, it just sees numbers with a colon in the middle. A better way to do this might be to use the 'last' command, as one of the fields it provides is the total log in time.
 

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xfs_logprint(8)                                               System Manager's Manual                                              xfs_logprint(8)

NAME
xfs_logprint - print the log of an XFS filesystem SYNOPSIS
xfs_logprint [ options ] device DESCRIPTION
xfs_logprint prints the log of an XFS filesystem (see xfs(5)). The device argument is the pathname of the partition or logical volume con- taining the filesystem. The device can be a regular file if the -f option is used. The contents of the filesystem remain undisturbed. There are two major modes of operation in xfs_logprint. One mode is better for filesystem operation debugging. It is called the transactional view and is enabled through the -t option. The transactional view prints only the portion of the log that pertains to recovery. In other words, it prints out complete transactions between the tail and the head. This view tries to display each transaction without regard to how they are split across log records. The second mode starts printing out information from the beginning of the log. Some error blocks might print out in the beginning because the last log record usually overlaps the oldest log record. A message is printed when the physical end of the log is reached and when the logical end of the log is reached. A log record view is displayed one record at a time. Transactions that span log records may not be decoded fully. OPTIONS
-b Extract and print buffer information. Only used in transactional view. -c Attempt to continue when an error is detected. -C filename Copy the log from the filesystem to the file filename. The log itself is not printed. -d Dump the log from front to end, printing where each log record is located on disk. -D Do not decode anything; just print data. -e Exit when an error is found in the log. Normally, xfs_logprint tries to continue and unwind from bad logs. However, sometimes it just dies in bad ways. Using this option prevents core dumps. -f Specifies that the filesystem image to be processed is stored in a regular file at device (see the mkfs.xfs(8) -d file option). This might happen if an image copy of a filesystem has been made into an ordinary file with xfs_copy(8). -l logdev External log device. Only for those filesystems which use an external log. -i Extract and print inode information. Only used in transactional view. -q Extract and print quota information. Only used in transactional view. -n Do not try and interpret log data; just interpret log header information. -o Also print buffer data in hex. Normally, buffer data is just decoded, so better information can be printed. -s start-block Override any notion of where to start printing. -t Print out the transactional view. SEE ALSO
mkfs.xfs(8), mount(8). xfs_logprint(8)
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