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Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Change the From: address on the fly for email sent from the command-line
It's very common to have cron jobs that send emails as their output, but the From: address is whatever account the cron job is running under, which is often not the address you want replies to go to. Here's a way to change the From: address right on the command line. What's happening here is that the "--" separates the options to the mail client from options for the sendmail backend. So the -f and -F get passed through to sendmail and interpreted there. This works on even on a system where postfix is the active mailer - looks like postfix supports the same options. I think it's possible to customize the From: address using mutt as a command line mailer also, but most servers don't have mutt preinstalled.

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

worse alternative to
worse alternative to ctrl+r: grep the history removing duplicates without sorting (case insensitive search).

Check if *hardware* is 32bit or 64bit
This command tell you if your hardware is 32 or 64 bits even if you install a 32bits OS on a 64 bits hardware. If your distro don't support the -q switch, try doing : $ grep &>/dev/null '\' /proc/cpuinfo && echo 64 bits || echo 32 bits

Archive all SVN repositories in platform indepenent form
This command dumps all SVN repositories inside of folder "repMainPath" (not recursively) to the folder "dumpPath", where one dump file will be created for each SVN repository.

Send apache log to syslog-ng
Send apache log to syslog-ng server without change configuration of syslog. Just add in httpd.conf or vhost conf.

Reboot as a different OS in Grub
This will reboot as the Grub 2 option.

Limit the cpu usage of a process
Similar to `cpulimit`, although `prlimit` can be found shipped with recent util-linux. Example: limit CPU consumption to 10% for a math problem which ordinarily takes up 100% CPU: Before: $ bc -l

Email an svn dump
Dumps a compressed svn backup to a file, and emails the files along with any messages as the body of the email


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