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Create a mirror of a local folder, on a remote server
Create a exact mirror of the local folder "/root/files", on remote server 'remote_server' using SSH command (listening on port 22) (all files & folders on destination server/folder will be deleted)

execute command on all files of certain types excluding folders that match pattern

Limit the cpu usage of a process
This will limit the average amount of CPU it consumes.

Dump and bz2compress a mysql db
To also move the db backup to another location you could pass the output to the dd command instead of a file $mysqldump -u user -h host -ppwd -B dbname | bzip2 -zc9 | dd ssh usr@server "dd of=db_dump"

Define shell variable HISTIGNORE so that comments (lines starting with #) appear in shell history
I was surprised to find that with RedHat bash, I could not find any comment lines (begining with #) in my bash shell history. Surprised because in Mageia Linux this works. It turns out that RedHat's bash will keep comment lines if in my .bashrc, I define: export HISTIGNORE=' cd "`*: PROMPT_COMMAND=?*?' Why have comment lines in shell history? It's a handy and convenient way to make proto-commands (to be completed later) and for storing brief text data that is searchable in shell history.

Create a persistent connection to a machine
Create a persistent SSH connection to the host in the background. Combine this with settings in your ~/.ssh/config: Host host ControlPath ~/.ssh/master-%r@%h:%p ControlMaster no All the SSH connections to the machine will then go through the persisten SSH socket. This is very useful if you are using SSH to synchronize files (using rsync/sftp/cvs/svn) on a regular basis because it won't create a new socket each time to open an ssh connection.

Test load balancers
With the "--resolve" switch, you can avoid doing DNS lookups or edit the /etc/hosts file, by providing the IP address for a domain directly. Useful if you have many servers with different IP addresses behind a load balancer. Of course, you would loop it: $ for IP in 10.11.0.{1..10}; do curl --resolve subdomain.example.com:80:$IP subdomain.example.com -I -s; done

Take a screenshot every 2 seconds
Take a screenshot every 2 seconds and save it as a png file

list human readable files
include in the list human readable hidden files too: $ file .* *|grep 'ASCII text'|sort -rk2 more reliable command: $ ls|xargs file|grep 'ASCII text'|sort -rk2 and include hidden files: $ ls -a|xargs file|grep 'ASCII text'|sort -rk2

Polkit: Force KDE apps to always recognize your display
KDE apps expect certain variables to be set, and unfortunately pkexec doesn’t set them by default. So, by setting this alias, it becomes possible to run, e.g. “pkexec kate” or “pkexec dolphin” and it’ll actually run.


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