Commands by trevorj (1)

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Check variable has been set

Recursively remove directory with many files quickly
rsync'ing an empty directory over a directory to be deleted recursively is much faster than using rm -rf, for various reasons. Relevant only for directories with really a lot of files.

Randomize lines in a file
Works in sort (GNU coreutils) 7.4, don't know when it was implemented but sometime the last 6 years.

Combine two mp3's or more into 1 long mp3
This just combines multiple mp3's into one mp3 file. Basically it is a easy join for mp3's

An alias to select a portion of your desktop and save it as an image.

Display the standard deviation of a column of numbers with awk

Export a directory to all clients via NFSv4, read/write.
This exports a directory to the world in read/write mode. It is useful for quick, temporary NFS exports. Consider restricting the clients to a subnet or to specific hosts for security reasons (the client can be specified before the colon). On the client: mount -t nfs4 hostname:/ /mountpoint To terminate all of the exports (after unmounting on the client): exportfs -u -a Leave out the fsid=0 option if you don't want NFSv4. This works under recent versions of Linux.

back ssh from firewalled hosts
host B (you) redirects a modem port (62220) to his local ssh. host A is a remote machine (the ones that issues the ssh cmd). once connected port 5497 is in listening mode on host B. host B just do a ssh 127.0.0.1 -p 5497 -l user and reaches the remote host'ssh. This can be used also for vnc and so on.

Get MX records for a domain

Watch Network Service Activity in Real-time

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