Commands using cat

Ever compress a file for the web by replacing all newline characters with nothing so it makes one nice big blob?

It is a great idea, however what about when you want to edit that file? ...Serious pain in the butt.

I ran into this today in that my only copy of a CSS file was "compressed" with no newlines.

I whipped this up and it converted back into nice human readable CSS :-)

It could be nicer, but it does the job.

The variable WIRELESSINTERFACE indicates your wireless interface

To sort hidden files first, simply switch the two inner `ls` commands.

I have this aliased to `dira`

`dir` is aliased to the simpler version with no hidden files:

attribution: Thanks to repellent on perlmonks.org

source: http://www.perlmonks.org/?node_id=684459

Displays SuSE release information

VARNAMES='ID FORENAME LASTNAME ADDRESS CITY PHONE MOBILE MAIL ...'

cat customer.csv | while read LINE ; do

COUNT=1

for VAR in $VARNAMES ; do

eval "${VAR}=`echo $LINE | /usr/bin/awk {'print $'$COUNT''}`"

let COUNT=COUNT+1

done

done

Maybe you have a CSV-File with addresses, where you have to process each contact (one per line, write each value to own variable). Of course you can define every variable, but this way is more simple and faster (to write).

VARNAMES includes the variable names. Pay attention: the number of names in VARNAMES have to be the same than in the CSV-file the fields. If the CSV is not seperated with ";", you can set the seperator after the awk-binary with -F"_" for example.

This is useful for displaying a portion of a FILE that contains an error at line NUMBER

replace "/usr/src/linux/kernel/signal.c" with any file you want and listen to its output ! :P

you can also replace "cat" with "echo" or anything you can come up with

have fun :-}

I'm sure almost everybody knows this by now. This command will pull the password for the admin login of any plesk machine.

Ok so it's rellay useless line and I sorry for that, furthermore that's nothing optimized at all...

At the beginning I didn't managed by using netstat -p to print out which process was handling that open port 4444, I realize at the end I was not root and security restrictions applied ;p

It's nevertheless a (good ?) way to see how ps(tree) works, as it acts exactly the same way by reading in /proc

So for a specific port, this line returns the calling command line of every thread that handle the associated socket

Maybe you know shorter ?

man tac

When there is a bad block in the middle of your file, you can see its begninning with `cat' and its end with `tac'. But both commands terminates with an error. So this sequence rebuilds a new file without badblock.

^V means CTRL-V

[ENTER] means ENTER key

xml with verbose commenting can be difficult to read. remove comments from xml.

This will view the console and assumes the screen is 80 characters wide.

Use /dev/vcs2 for the next virtual console.. etc.

Adds the stdout (standard output) to the beginning of logfile.txt. Change "command" to whatever command you like, such as 'ls' or 'date', etc. It does this by adding the output to a temporary file, then adding the previous contents of logfile.txt to the temp file, then copying the new contents back to the logfile.txt and removing the temp file.

Searches /var/log/secure for smtp connections then lists these by number of connections made and hosts.

Searches the /var/log/secure log file for Failed and/or invalid user log in attempts.

Good old cat & output redirection. Using this method you can combine all kinds of things - even mpeg files. My video camera makes a series of .mpeg files that are broken into 4gb chunks. Using this command I can easily join them together. Even better, combined with the cp command the files can be copied and joined in one step.

Place microphone near speaker and enjoy