The gunzip utility can uncompress logfiles that are gzipped in archives, but this is not needed. To read a logfile that is gzipped, you can also use this command to print the contents to a terminal and not bother uncompressing the file. This allows reading log files in /var/log without needing root access.
This is an example, reading an archived syslog file.
4.4 Thu Mar 05 jason@Yog-Sothoth 0: $ gunzip -k -c /var/log/syslog.6.gz | head -n 10 Feb 28 08:35:34 Yog-Sothoth rsyslogd: [origin software="rsyslogd" swVersion="8.32.0" x-pid="1471" x-info="http://www.rsyslog.com"] rsyslogd was HUPed Feb 28 08:37:01 Yog-Sothoth anacron[1802]: Job `cron.daily' terminated Feb 28 08:37:01 Yog-Sothoth anacron[1802]: Normal exit (1 job run) Feb 28 08:39:01 Yog-Sothoth CRON[8189]: Authentication failure Feb 28 08:39:01 Yog-Sothoth cron[1979]: Authentication failure Feb 28 08:39:04 Yog-Sothoth systemd[1]: Starting Clean php session files... Feb 28 08:39:04 Yog-Sothoth systemd[1]: Started Clean php session files. Feb 28 08:44:53 Yog-Sothoth systemd[1]: Starting Cleanup of Temporary Directories... Feb 28 08:44:53 Yog-Sothoth systemd[1]: Started Cleanup of Temporary Directories. Feb 28 08:45:01 Yog-Sothoth CRON[1828]: Authentication failure |
Another example, using zcat. This also can read the contents of the file without the need to uncompress it first and then cat the extracted file.
4.4 Thu Mar 05 jason@Yog-Sothoth 0: $ zcat /var/log/syslog.6.gz | head -n 10 Feb 28 08:35:34 Yog-Sothoth rsyslogd: [origin software="rsyslogd" swVersion="8.32.0" x-pid="1471" x-info="http://www.rsyslog.com"] rsyslogd was HUPed Feb 28 08:37:01 Yog-Sothoth anacron[1802]: Job `cron.daily' terminated Feb 28 08:37:01 Yog-Sothoth anacron[1802]: Normal exit (1 job run) Feb 28 08:39:01 Yog-Sothoth CRON[8189]: Authentication failure Feb 28 08:39:01 Yog-Sothoth cron[1979]: Authentication failure Feb 28 08:39:04 Yog-Sothoth systemd[1]: Starting Clean php session files... Feb 28 08:39:04 Yog-Sothoth systemd[1]: Started Clean php session files. Feb 28 08:44:53 Yog-Sothoth systemd[1]: Starting Cleanup of Temporary Directories... Feb 28 08:44:53 Yog-Sothoth systemd[1]: Started Cleanup of Temporary Directories. Feb 28 08:45:01 Yog-Sothoth CRON[1828]: Authentication failure |
This is a very good tip for finding errors in your Linux system. It appears that I have CRON deamon authentication errors, but I can fix these eventually.