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Full Discussion: How to read a fast written log file at Real time speed?
Top Forums UNIX for Advanced & Expert Users How to read a fast written log file at Real time speed? Post 302936631 by cool.aquarian on Thursday 26th of February 2015 09:00:32 PM
Old 02-26-2015
Quote:
Originally Posted by achenle
That's not really an easy problem to solve. Any solution that meets your requirements has to take into account specifics of the OS, the file system, and even the physical hardware. Obviously such a solution isn't going to be very portable.

The first thing you have to figure out is what's fast enough? Because there's always going to be some delay in reading data from the file after it's been written.

You might be better served interposing something into the logging stream that splits the stream into two - one to the original logging system and one into your real-time parser.
Thanks for your post.
About what is fast enough, a delay of 30 seconds or so would be within the accepted level. But I have seen that on average, the tail command is able to read less than 70% of the file(within 10 minutes) before the file gets rolled over and script throws the error (as the log files are present on a shared NFS mount):
Code:
tail: error reading `<file-path>': Stale NFS file handle

Last edited by cool.aquarian; 02-26-2015 at 10:17 PM..
 

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LEARN ABOUT CENTOS

mount.nfs

MOUNT.NFS(8)						      System Manager's Manual						      MOUNT.NFS(8)

NAME

       mount.nfs, mount.nfs4 - mount a Network File System

SYNOPSIS

       mount.nfs remotetarget dir [-rvVwfnsh ] [-o options]

DESCRIPTION

       mount.nfs is a part of nfs(5) utilities package, which provides NFS client functionality.

       mount.nfs  is  meant to be used by the mount(8) command for mounting NFS shares. This subcommand, however, can also be used as a standalone
       command with limited functionality.

       mount.nfs4 is used for mounting NFSv4 file system, while mount.nfs is used to mount NFS file systems versions 3 or 2.   remotetarget  is  a
       server share usually in the form of servername:/path/to/share.  dir is the directory on which the file system is to be mounted.

OPTIONS

       -r     Mount file system readonly.

       -v     Be verbose.

       -V     Print version.

       -w     Mount file system read-write.

       -f     Fake mount. Don't actually call the mount system call.

       -n     Do not update /etc/mtab.	By default, an entry is created in /etc/mtab for every mounted file system. Use this option to skip making
	      an entry.

       -s     Tolerate sloppy mount options rather than fail.

       -h     Print help message.

       nfsoptions
	      Refer to nfs(5) or mount(8) manual pages.

NOTE

       For further information please refer nfs(5) and mount(8) manual pages.

FILES

       /etc/fstab	 file system table

       /etc/mtab	 table of mounted file systems

SEE ALSO

       nfs(5), mount(8),

AUTHOR

       Amit Gud <agud@redhat.com>

								    5 Jun 2006							      MOUNT.NFS(8)
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