Ubuntu Manpage: since - display content of a file since the last time

NAME

       since - display content of a file since the last time

SYNOPSIS

       since [-aefhlmnqvxz] [-d seconds] [-s file] files

DESCRIPTION

       since  is  a  utility  designed  to  monitor  log files.  since is similar to tail(2) as it also displays
       information appended to a file.  However since only displays the data which has been added since the last
       time  since  was  run.  If  since is run on a particular file for the first time, then the entire file is
       displayed.

EXAMPLE

       since /var/log/apache/{access,error}_log > /dev/null
       lynx --dump http://localhost/ > /dev/null
       since /var/log/apache/{access,error}_log

OPTIONS

-a Make updates to the since state files atomic. This option configures since to use a temporary file
and a rename(2) instead of updating the state file in situ.

-d seconds
Specify the number of integer seconds to wait between polling files for changes. This option is
only relevant in conjunction with the -f option and if the inotify mechanism is not being used.

-e Print the header lines to standard error instead of standard output.

-f Follow the specified files. This option is analogous to tail -f as the files are also polled for
changes until the process is interrupted.

-h Print a terse help message.

-l Relaxed mode. If some data files are inaccessible since will not fail completely.

-m Disable mmap(2), use read(2) instead to access state and data files. Note that for certain
smaller io operations read(2) may be used even if this option has not been given.

-n Do not update the .since file which keeps track of file growth.

-q Make the utility operate more quietly.

-s filename
Specify the state file explicitly. Using this option will also disable the use of fallback state
files.

-v Increase the verbosity. This option can be given multiple times.

-x Ignore file arguments which have compressed extensions.

-z Discard output. Similar to redirecting the output to /dev/null, but faster. If used in conjunction
with the -f option, only the initial output will be discarded.

FILES

       .since

              State file recording the length of the previously displayed files.  The location of the  file  can
              be  set on the command line using the -s option. If this option is not given, since will check the
              SINCE environment variable for the location of the state file. If the SINCE  environment  variable
              has  not  been  set  since will use the HOME environment variable and store the information in the
              file $HOME/.since.  If the HOME variable is not set, since will use a getpwuid(3) lookup.  If  all
              these fail will use the file /tmp/since.

BUGS

       since  uses  the inode of a file as its key, if that inode is recycled since will get confused.  since is
       not particularly efficient when storing or looking up the stat(2) information.  Functionality  equivalent
       to since can probably be achieved with a number of trivial shell scripts.

COPYING

       since  may  only  be  used, distributed and modified in accordance with the terms of the GPL (GNU General
       Public License) version 3 or newer as published by the FSF (Free Software Foundation).