logtail (linux command)

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license: 
Version:
Developer / owner:
Craig H. Rowland (original C version)
Paul Slootman (Perl translated version)

Short description:

Manual page and help for the logtail linux command. The logtail program reads the file specified in the parameter (which is usually a log file) and outputs to standard output the part that it has not yet read during its previous run. It reads a sufficient number of bytes of data, assuming that changes made to the file have only been added as new characters.

 

 

Man page output

man logtail
LOGTAIL(8)                        logtail manual                        LOGTAIL(8)

NAME
       logtail - print log file lines that have not been read

SYNOPSIS
       logtail [-t] -flogfile [-ooffsetfile]

DESCRIPTION
       logtail reads a specified file (usually a log file) and writes to the stan‐
       dard output that part of it which has not been read  by  previous  runs  of
       logtail.   It  prints  the appropriate number of bytes from the end of log‐
       file, assuming that all changes that are made to it are to add new  charac‐
       ters to it.

       logfile must be a plain file.  A symlink is not allowed.

       logtail  stores  the information about how much of it has already been read
       in a separate file called offsetfile.  offsetfile can be omitted.  If omit‐
       ted,  the  file  named  logfile.offset in the same directory which contains
       logfile is used by default.

       If offsetfile is not empty, the inode of logfile is checked.  If the  inode
       is  changed,  logtail  simply  prints the entire file.  If the inode is not
       changed but logfile is shorter than it was at the last run of  logtail,  it
       writes a warning message to the standard output.

OPTIONS
       -f     logfile to be read after offset

       -o     offsetfile stores offset of previous run

       -t     test mode - do not change offset in offsetfile

RETURN VALUES
       0      successful

       65     cannot get the size of logfile

       66     logfile does not exist, is not a plain file, or is not readable

       73     cannot write offsetfile

AUTHOR
       The  original  logtail  was  written  in  C  by  Craig  H.  Rowland  <crow‐
       land@psionic.com>.  This version of logtail is a Perl  reimplementation  by
       Paul  Slootman  <paul@debian.org>.   Enhanced  by  the Debian Logcheck Team
       <logcheck@packages.debian.org>.

       This manual was written by Oohara Yuuma <oohara@libra.interq.or.jp>.

SEE ALSO
       logcheck(8)

Debian                           Fri, 19 Nov 2004                       LOGTAIL(8)

 

 

Help output

sudo logtail --help
/usr/sbin/logtail version [unknown] calling Getopt::Std::getopts (version 1.12 [paranoid]),
running under Perl version 5.28.1.

Usage: logtail [-OPTIONS [-MORE_OPTIONS]] [--] [PROGRAM_ARG1 ...]

The following single-character options are accepted:
        With arguments: -f -o
        Boolean (without arguments): -t

Options may be merged together.  -- stops processing of options.
Space is not required between options and their arguments.
  [Now continuing due to backward compatibility and excessive paranoia.
   See 'perldoc Getopt::Std' about $Getopt::Std::STANDARD_HELP_VERSION.]
No logfile to read. Use -f [LOGFILE].

 

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