Commands using ssh (347)

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Get Futurama quotations from slashdot.org servers

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.

Revert back all files currently checked out by Perforce SCM for edit

Fetch all GPG keys that are currently missing in your keyring
For instance, if people have signed your key, this will fetch the signers' keys.

Optimal way of deleting huge numbers of files
Using xargs is better than: $ find /path/to/dir -type f -exec rm \-f {} \; as the -exec switch uses a separate process for each remove. xargs splits the streamed files into more managable subsets so less processes are required.

Reboot machine when everything is hanging
If the machine is hanging and the only help would be the power button, this key-combination will help to reboot your machine (more or less) gracefully. R - gives back control of the keyboard S - issues a sync E - sends all processes but init the term singal I - sends all processes but init the kill signal U - mounts all filesystem ro to prevent a fsck at reboot B - reboots the system Save your file before trying this out, this will reboot your machine without warning! http://en.wikipedia.org/wiki/Magic_SysRq_key

Just convert your all books DJVU format to PDF, with one line

convert ascii string to hex
just a bit simpler

Extract all of the files on an RPM on a non-RPM *nix

send raw data (hex written)using UDP to an IP and port
Use it to send raw data to a networked device. Used to interact with relay controller board whose documentation is lost, so use wireshark to sniff the sent data and replayed using the command.


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