All commands

This assumes your mail log is /var/log/mail.log

From 'man netstat'

"netstat -i | -I interface [-abdnt] [-f address_family] [-M core] [-N system]

Show the state of all network interfaces or a single interface

which have been auto-configured (interfaces statically configured

into a system, but not located at boot time are not shown). An

asterisk (``*'') after an interface name indicates that the

interface is ``down''. If -a is also present, multicast

addresses currently in use are shown for each Ethernet interface

and for each IP interface address. Multicast addresses are shown

on separate lines following the interface address with which they

are associated. If -b is also present, show the number of bytes

in and out. If -d is also present, show the number of dropped

packets. If -t is also present, show the contents of watchdog

timers."

The script contains a single command:

cd /a/long/directory/path/i/can/never/remember

the $15 may change for you depending on your distro, etc...

This is a nice way to kill processes.. the example here is for firefox!!! substitute firefox for whatever the process name is...

see sample output

More info here:

http://nagioswiki.com/wiki/index.php/Autocreating_Nagios_Configuration_with_Nmap_and_Nmap2Nagios.pl

friends don't let friends use Robocopy!

from http://matt.ucc.asn.au/ssh-xfer/

"ssh-xfer is a hackish but handy way of transferring files from remote hosts to your local computer. Firstly, you need to run a slightly modified SSH authentication agent program on your local computer. Patches are available for both OpenSSH and PuTTY, see below. If you haven't used a SSH agent program before, this article seems to be reasonable, or you can look at the OpenSSH/PuTTY docs.

You don't need any modifications to your ssh client or server programs - only the modified SSH authentication agent, and the extra ssh-xfer program."

In the sample output, I pressed ctrl+r and typed the letters las. I can't imagine how much typing this has saved me.

To save the result, redirect the output to another file.

any HTTP requests to the machine on the specified port will be redirected to http://www.whatevs.com... quick, dirty, works fine for sites w/

Turn off almost all of dig's output except for what you'd see in a zone file. This can also be put into ~/.digrc.

This command is somewhat similar to 'nice', but constrains I/O usage rather than CPU usage. In particular, the '-c3' flag tells the OS to only allow the process to do I/O when nothing else is pending. This dramatically increases the responsiveness of the rest of the system if the process is doing heavy I/O.

There's also a '-p' flag, to set the priority of an already-running process.

The Linux /dev/full file simulates a "disk full" condition, and can be used to verify how a program handles this situation.

In particular, several programming language implementations do not print error diagnostics (nor exit with error status) when I/O errors like this occur, unless the programmer has taken additional steps. That is, simple code in these languages does not fail safely. In addition to Perl, C, C++, Tcl, and Lua (for some functions) also appear not to fail safely.

This command install Apache 2 and other utilities on CentOS

The backslash avoids any 'rm' alias that might be present and runs the 'rm' command in $PATH instead.

In a misguided attempt to be more "friendly", some Linux distributions (or sites/etc.) alias 'rm' to 'rm -i'. Unfortunately, this trains users to expect that files won't actually be deleted until they okay it. This expectation will fail with catastrophic results when they use other distributions, move to other sites, etc., and doesn't really even work 100% even with the alias. It's too late to fix 'rm', but '\rm' should work everywhere (under bash).

creates a new tab for each of N servers in listofservers.txt and ssh's to said servers

then, try the "send to all sessions" feature of konsole to do the same work on all servers at the same time. BIG time saver, but be careful!

The last ; is important. example:

time { rm -rf /folder/bar && mkdir -p /folder/bar ; echo "done" ; }

command is a bash builtin

converts encoding of a file to unix utf-8

useful for data files that contain what would be usable ascii text but are encoded as mpeg or some other encoding that prevents you from doing common manipulations like 'sed'