Commands for the wicked (112)

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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"

simple backup with rsync
With this cron, rsync begins to sinchronize the contents of the local directory on /[VIPdirectory] with the directory /backup/[VIPdirectory] on the remote server X.X.X.X. Previously we need working on public/private-keys ssh to guarantee the acces to the remote server on X.X.X.X

Grep without having it show its own process in the results
The trick here is to use the brackets [ ] around any one of the characters of the grep string. This uses the fact that [?] is a character class of one letter and will be removed when parsed by the shell. This is useful when you want to parse the output of grep or use the return value in an if-statement without having its own process causing it to erroneously return TRUE.

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"

Find which service was used by which port number

Check if running in an X session
If you want to display a dialog (using xdialog/kdialog/zenity) you need to make sure that you have a valid X session. Checks for the existence of the DISPLAY variable.

SSH to a machine's internet address if it is not present on your local network
Ping machine once, waiting 1 second for response until failing. Upon fail, ssh globally, otherwise ssh locally.

String to binary
Cool but useless.

Find usb device
I often use it to find recently added ou removed device, or using find in /dev, or anything similar. Just run the command, plug the device, and wait to see him and only him

run command on a group of nodes in parallel


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