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What's this? is the place to record those command-line gems that you return to again and again. That way others can gain from your CLI wisdom and you from theirs too. All commands can be commented on, discussed and voted up or down.

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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.

Remove everything except that file
it will remove everything except the file names matching you can use also use wildcards

zsh only: access a file when you don't know the path, if it is in PATH
Say you want to execute 'file' on the command 'top' (to determine what type of file it is); but you don't know where 'top' resides: preface the argument with = and zsh will implicitly prepend the path.

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"

List processes sorted by CPU usage

Add GPG key easy - oneliner
Replace KEY with GPG key. This command will load GPG key and add it to your system so you can use software from third party repos etc.

lotto generator

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"

identify exported sonames in a path
This provides a list of shared object names (sonames) that are exported by a given tree. This is usually useful to make sure that a given required dependency (NEEDED entry) is present in a firmware image tree. The shorter (usable) version for it would be $ scanelf -RBSq -F "+S#f" But I used the verbose parameters in the command above, for explanation.

Determine space taken by files of certain type
Just how much space are those zillions of database logs taking up ? How much will you gain on a compression rate of say 80% ? This little line gives you a good start for your calculations.

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Follow the Tweets.

Every new command is wrapped in a tweet and posted to Twitter. Following the stream is a great way of staying abreast of the latest commands. For the more discerning, there are Twitter accounts for commands that get a minimum of 3 and 10 votes - that way only the great commands get tweeted.


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Use your favourite RSS aggregator to stay in touch with the latest commands. There are feeds mirroring the 3 Twitter streams as well as for virtually every other subset (users, tags, functions,…):

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