tail
****

.. highlight:: bash

Output appended data as the file grows::

  tail -f /etc/httpd/logs/error_log

Compress
========

From `View compressed .gz files without uncompressing using Z commands`_

To view compressed log files::

  # -f compressed and uncompressed
  zcat -f dmesg | more

  # no need for -f
  zless dmesg.1.gz
  zmore dmesg.1.gz

  # -i case insensitive
  zgrep -i usb dmesg.1.gz | more

  # diff
  zcmp dmesg.1.gz dmesg.2.gz
  zdiff dmesg.1.gz dmesg.2.gz | more

Last x Lines
============

Last 30 lines of ``catalina.out``::

  tail -n30 /opt/tomcat5/logs/catalina.out

Long Lines
==========

`Tail a log file with long lines truncated`_::

  tail -f logfile.log | cut -b 1-80

Also useful for looking at different parts of the line,
e.g. ``cut -b 50-100`` shows columns 50 through 100.

Or even smarter, use ``tput cols`` to tell you the width of the
terminal::

  tail -f logfile.log | cut -b -$(tput cols)


.. _`Tail a log file with long lines truncated`: http://www.commandlinefu.com/commands/view/1710/tail-a-log-file-with-long-lines-truncated
.. _`View compressed .gz files without uncompressing using Z commands`: http://www.blackmoreops.com/2014/08/01/z-commands-view-compressed-tar-gz-files-without-uncompressing/