Commands by bucciarati (4)

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Check if a machine is online
PING parameters c 1 limits to 1 pinging attempt q makes the command quiet (or silent mode) /dev/null 2>&1 is to remove the display && echo ONLINE is executed if previous command is successful (return value 0) || echo OFFLINE is executed otherwise (return value of 1 if unreachable or 2 if you're offline yourself). I personally use this command as an alias with a predefined machine name but there are at least 2 improvements that may be done. Asking for the machine name or IP Escaping the output so that it displays ONLINE in green and OFFLINE in red (for instance).

Convert clipboard HTML content to markdown (for github, trello, etc)
I always wanted to be able to copy formatted HTML, like from emails, on trello cards or READMEs... but the formatting is always wrong... But from this two links: * https://jeremywsherman.com/blog/2012/02/08/pasting-html-into-markdown/ * http://stackoverflow.com/questions/3261379/getting-html-source-or-rich-text-from-the-x-clipboard For instance, to to copy an formatted email to a trello card, just: 1. Select the email body 2. run: xclip -selection clipboard -o -t text/html | pandoc -f html -t markdown_github - | xclip -i -t text/plain 3. Paste in your trello card 4. Profit! 8-)

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Printable random characters
Reads psuedorandom bytes from /dev/urandom, filtering out non-printable ones. Other character classes can be used, such as [:alpha:], [:digit:] and [:alnum:]. To get a string of 10 lowercase letters: $ tr -dc '[:lower:]' < /dev/urandom | head -c 10

Convert seconds to [DD:][HH:]MM:SS
Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

Pull Total Memory Usage In Virtual Environment
This command basically adds up all of the individual instances processes and gives you a grand total for used memory in that instance alone.

Rename all .jpeg and .JPG files to .jpg

Print all lines between two line numbers
This command uses awk(1) to print all lines between two known line numbers in a file. Useful for seeing output in a log file, where the line numbers are known. The above command will print all lines between, and including, lines 3 and 6.

Instead of writing a multiline if/then/else/fi construct you can do that by one line
instead of writing: if [[ "$1" == "$2" ]]; then echo "$1 is equal $2" else echo "$1 differs from $2" fi do write: [[ "$1" == "$2" ]] && echo "$1 is equal $2" || echo "$1 differs from $2"

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