Commands using head (314)

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Create sqlite db and store image
Creates a simple sqlite db (img.db) inserts /tmp/Q.jpg on base64 an recorvers it as /tmp/W.jpg

Calculate the mean or average of a single column of numbers in a text file
single-column-numbers.txt is a text file with 22658 rows (numbers) in a single column. Each number can range from 0 to 134298679.533591 and the dot is for the decimals. This is done with perl because awk can't sum such high numbers.

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" }

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"

Kill a broken ssh connection
This is useful for example if you are on ssh in a server and the server goes down without letting you out. This is part of a larget sets of escape sequences provided by ssh. You can find them with ~? Here's the list: ~. - terminate connection (and any multiplexed sessions) ~B - send a BREAK to the remote system ~C - open a command line ~R - request rekey ~V/v - decrease/increase verbosity (LogLevel) ~^Z - suspend ssh ~# - list forwarded connections ~& - background ssh (when waiting for connections to terminate) ~? - this message ~~ - send the escape character by typing it twice (Note that escapes are only recognized immediately after newline.)

Check motherboard manufacturer, product name, version and serial number
Very slick way to check your motherboard manufacturer, product name, version and serial number.

Figure out your work output for the day
Figures out what has changed in the last 12 hours. Change the author to yourself, change the time since to whatever you want.

get only time of execution of a command without his output

Ping all hosts on 192.168.1.0/24

Add all files not under subversion control


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