Admin Linux

Linux command line tips

I love the Linux command line. I don’t know how to categorize the tips I have collected so I’m dumping them here for the time being.

The newer netstat
In the old days I used to constantly do

$ netstat -an|grep LISTEN|grep <PORT>

to see what tcp ports I had processes listening on. While that is very helpful, it doesn’t tell you the listening process. A better approach:

$ lsof -i tcp:<PORT>

where is 22, 80 or whatever you want to look for. lsof does show the process.

Repeat last argument

I am constantly doing things like

$ grep <string> <big-file> > /tmp/results

and then I want to have a look at that file but I don’t want to type in

$ more /tmp/results

so what do I do?

I type this to give me the last argument:

$ more !$

My fingers have memorized that pattern and so I do it without conscious thought, and you’re holding down the SHIFT key so it can be typed very quickly.

But sometimes I can’t wait to type even that. I want to collect the grep results into a file in case there were a lot of matches, but I also want to see the matching results on my screen as soon as they are available. What do I do? Use tee, as in:

$ grep <string> <big-filez> |tee /tmp/results|more

Cool, huh?

More Obscure stuff
A cool blog with lots of good, obscure tips, generally more technical than the ones above, is

To be continued…


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