Comments on: 10 Awesome Examples for Viewing Huge Log Files in Unix

By: ks

ks — Wed, 02 Mar 2011 23:45:21 +0000

A nice and handy tutorial. A few comments about the above comment by @logan:

$ cat logfile | less
has the same effect as
$ less logfile
and hence the use of the pipe is redundant (‘$’ stands for the command prompt). Both lets you scroll through the logfile and search for pattern using ‘/’ and ‘?’ (similar to vim).

However, the second
$ cat logfile | less | grep “PATTERN”
does not let you scroll, but the following
$ grep “PATTERN” logfile | less
will — through only the the lines that has the matching pattern “PATTERN”.

By: logan

logan — Mon, 21 Feb 2011 06:11:11 +0000

or you can always use

cat logfile | less

which lets you scroll through it

cat logfile | less | grep “PATTERN”

which lets you scroll through matching entries
I search for sshd for my auth.log file and can see all and only the ssh server entries

By: anton

anton — Fri, 06 Aug 2010 09:24:12 +0000

Is the following any better (i.e. more efficient) than zcat logfile.gz | tail ???

# emulate ztail ???

zless +F logfile.gz

By: Brad

Brad — Wed, 14 Jul 2010 14:49:33 +0000

You showed zcat, but there is also bzcat and lzcat, and probably a few others. so if you have a file that is bzip2′d or lzma’d, then you can use bzcat and lzcat respectively to display them. Also, it can be piped to the less command so it can be scrolled across the terminal.

By: HowTo: The Ultimate Logrotate Command Tutorial with 10 Examples

HowTo: The Ultimate Logrotate Command Tutorial with 10 Examples — Wed, 14 Jul 2010 06:03:49 +0000

[...] Also, if you are having huge log files, you can use: 10 Awesome Examples for Viewing Huge Log Files in Unix [...]

By: Bipin

Bipin — Thu, 06 May 2010 11:49:17 +0000

Great stuffs. Thanks for sharing.

By: Ted

Ted — Sun, 13 Sep 2009 06:06:03 +0000

The sed tip I will use for sure and I also like the tail -f |grep. Thank you Ramesh.

Any chance you will be posting your most useful sed commands from your note book at some time?

By: 3 Methods To View tail -f output of Multiple Log Files in One Terminal

3 Methods To View tail -f output of Multiple Log Files in One Terminal — Wed, 09 Sep 2009 06:03:03 +0000

[...] Typically you may open multiple terminals to view tail -f of multiple files as we explained in our previous 10 examples to view unix log files. [...]

By: ShekarKCB

ShekarKCB — Mon, 24 Aug 2009 11:13:22 +0000

Nice Article, uses of head, tail, and sed were nicely covered. Thanks for the same.

By: Ramesh Natarajan

Ramesh Natarajan — Fri, 14 Aug 2009 14:56:03 +0000

@Robert,

Sed can do lot of amazing things. But it is hard to remember those on top of your head. I have close to 100 sed command that solves some common problem in a notebook, which I copy/paste whenever nedded.

Example 1 of this article is in that list.

@Nico,

Thanks for pointing that out. Most of us forget that grep can be combined with “tail -f”. This indeed can be very handy.

@Nicholas,

Don’t worry. I’ve done similar mistakes several times. So, I can related to it.

@Ashish, @Koen

I’m very glad that you found this article helpful.

@Ronald,

Yeah. That is the beauty of Unix. We can do amazing things with linux commands that were not even clearly mentioned in the manual. This is also the reason Windows admins don’t like Linux, as they hate reading manuals. Even when they read the manuals, it is not really explained very well.