Commands using head (314)

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What is my public IP address
It's easier then the listed command, I'm thinking. but doesn't matter much--its closer to personal preference really.

Get sunrise and sunset times
This will get the sunrise and sunset times of a specific location. To be able to determine $l you need to first go to http://weather.yahoo.com/ and look up your location. The last numbers in the URL will be the $l Instead of forecastrss?w=$l you can also use forecastrss?p=$l and use the RSS link of the city you found. Also see http://developer.yahoo.com/weather/ for more information

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" }

Transfer Entire recursive from one host to another. Only copies files that are newer or do not exist
From opposite host To copy remote to local rsync -aE -e "ssh -pPortnumber" user@hostA:directory target_dir

Top 10 Memory Processes (reduced output to applications and %usage only)
Top 10 Memory Processes (reduced output to applications and %usage only)

Display 6 largest installed RPMs sorted by size (descending)
Low on disk space? Check the largest installed RPMs for delete canditates.

Save current layout of top
'top' has fancy layout modes where you can have several windows with different things displayed. You can configure a layout and then save it with 'W'. It will then be restored every time you run top. E.g. to have two colored windows, one sorted by CPU usage, the other by memory usage, run top $ top then press the keys $ and then as you don?t want to repeat this the next time: $

Localize provenance of current established connections
Sample command to obtain a list of geographic localization for established connections, extracted from netstat. Need geoiplookup command ( part of geoip package under CentOS)

Prepend a text to a file.
Syntax: $ prepend content to add [filename] Uses ed, so no temp files created.

Create QR codes from a URL.
QR codes are those funny square 2d bar codes that everyone seems to be pointing their smart phones at. Try the following... $ qrurl http://xkcd.com Then open qr.*.png in your favorite image viewer. Point your the bar code reader on your smart phone at the code, and you'll shortly be reading xkcd on your phone. URLs are not the only thing that can be encoded by QR codes... short texts (to around 2K) can be encoded this way, although this function doesn't do any URL encoding, so unless you want to do that by hand it won't be useful for that.


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