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Full Discussion: grep sed and a loop
Top Forums UNIX for Dummies Questions & Answers grep sed and a loop Post 302521308 by agama on Tuesday 10th of May 2011 10:32:32 PM
Old 05-10-2011
It sounds like you're working with a daemon's log file and if so you'll need to be careful. If you overlay the open log file, you'll stop seeing updates to the file as you will have unlinked the open file from the directory and replaced it with a static file that you marked up with hash (#) signs.

I think you have two choices:

1) use tail -f to read the log file and pipe the output through grep or awk to do what you need. This is probably easiest.

2) if your log file has timestamps then you can run your search periodically. With each run save the last time stamp in the log file, tuck it away in a /tmp file or something, and only process messages in the log that have a timestamp greater than the last one saved.

Small sample of using tail:
Code:
tail -f /var/log/foo | grep "Can not load CRL"  >capture-file

 

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LEARN ABOUT SUSE

nislog

nislog(1M)                                                System Administration Commands                                                nislog(1M)

NAME

       nislog - display the contents of the NIS+ transaction log

SYNOPSIS

       /usr/sbin/nislog [-h num | -t num]  [-v] [directory...]

DESCRIPTION

       nislog  displays  the  contents of the NIS+ server transaction log on the standard output. This command can be used to track changes in the
       namespace. The /var/nis/trans.log file contains the transaction log maintained by the NIS+ server. When updates occur, they are  logged  to
       this  file  and  then  propagated  to replicas as log transactions.  When the log is checkpointed, updates that have been propagated to the
       replicas are removed.

       The nislog command can only be run on an NIS+ server by superuser. It displays the log entries for that server only.

       If directory is not specified, the entire log is searched. Otherwise, only those logs entries that correspond to the specified  directories
       are displayed.

OPTIONS

       -h num          Display num transactions from the ``head'' of the log. If the numeric parameter is  0, only the log header is displayed.

       -t num          Display  num transactions from the ``tail'' of the log. If the numeric parameter is  0, only the log header is displayed.

       -v              Verbose mode.

FILES

       /var/nis/trans.log      transaction log

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE         |      ATTRIBUTE VALUE        |
       +-----------------------------+-----------------------------+
       |Availability                 |SUNWnisu                     |
       +-----------------------------+-----------------------------+

SEE ALSO

       nis+(1), rpc.nisd(1M), nisfiles(4), attributes(5)

NOTES

       NIS+  might  not  be  supported in future releases of the SolarisTM Operating Environment. Tools to aid the migration from NIS+ to LDAP are
       available in the Solaris 9 operating environment. For more information, visit http://www.sun.com/directory/nisplus/transition.html.

SunOS 5.10                                                          12 Dec 2001                                                         nislog(1M)
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