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gh or "grep history" - define a function gh combining history and grep to save typing
By defining a function "gh" as shown here, it saves me typing "history | grep" every time I need to search my shell history because now I only have to type "gh". A nifty time saver :-) You can also add the "gh" function definition to your .bashrc so it is defined each time you login. (updated 2015_01_29: changed from hg to gh to avoid clash with that other hg command. mnemonic: gh = grep history)

Numeric zero padding file rename
This uses Perl's rename utility (you may have to call it as prename on your box) and won't choke on spaces or other characters in filenames. It will also zero pad a number even in filenames like "vacation-4.jpg".

Prettify an XML file
Generated XML files often are poorly formatted. Use this command to properly indent and normalize the file in-place.

Make redirects to localhost via /etc/hosts more interesting
Normally when a site is blocked through /etc/hosts, traffic is just being redirected to a non-existent server that isn't going to respond. This helps get your point across a little more clearly than a browser timeout. Of course you could use any number of codes: http://en.wikipedia.org/wiki/List_of_HTTP_status_codes Obviously, this command can be added to init-rc.d, and more sophisticated responses can be given. Seems noteworthy to mention that the information sent from the browser can be parsed using the bash READ builtin (such as 'while read -t 1 statement; do parsing'), and the connection stays open until the script exits. Take care that you must use EXEC:'bash -c foo.sh', as 'execvp' (socat's method for executing scripts) invokes 'sh', not 'bash'.

How to stop MAC Address via IPTables
edit the /etc/sysconfig/iptables file and try to work whit this: -A INPUT -i (interface) -m mac (mac address) -j ACCEPT/DROP

'hpc' in the box - starts a maximum of n compute commands modulo n controlled in parallel
the block of the loop is useful whenever you have huge junks of similar jobs, e.g., convert high res images to thumbnails, and make usage out of all the SMP power on your compute box without flooding the system. note: c is used as counter and the random sleep $ r=`echo $RANDOM%5 |bc`; echo "sleep $r"; sleep $r is just used as a dummy command.

move up through directories faster (set in your /etc/profile or .bash_profile)
You can also remove the "&& pwd" if you don't want it to print out each directory as it moves up.

display systemd log entries for sshd using "no-pager" (a bit like in pre-systemd: grep sshd /var/log/messages)
In pre-systemd systems, something like: "# grep sshd /var/log/messages" would display log events in /var/log/messages containing "sshd". # journalctl -u sshd --no-pager The above command displays similar results for systemd systems. (Note that this needs to be run with root permissions to access the log data.)

converting vertical line to horizontal line

pdfcount: get number of pages in a PDF file


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