Commands by purehate (3)

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do something else while waiting for an event, such as reboot
until (ssh [email protected] 2> /dev/null); do date; sleep 15; done In this case will execute "date" then "sleep 15" until we are able to ssh into server, such as after a reboot Could also be like: until ( ping 10.1.1.39 1> /dev/null); do echo "server 10.1.1.39 is down"; sleep 15; done

Convert CSV to JSON
Replace 'csv_file.csv' with your filename.

Counts number of lines
Counts number of lines of code in *.h and *.cc files

execute your commands hiding secret bits from history records
$ wget --user=username --password="$password" http://example.org/ Instead of hiding commands entirely from history, I prefer to use "read" to put the password into a variable, and then use that variable in the commands instead of the password. Without the "-e" and "-s" it should work in any bourne-type shell, but the -s is what makes sure the password doesn't get echoed to the screen at all. (-e makes editing work a bit better)

Selecting a random file/folder of a folder
Also looks in subfolders

Generate a Random MAC address
Use the following variation for FreeBSD: $ openssl rand 6 | xxd -p | sed 's/\(..\)/\1:/g; s/:$//'

Rename files in batch

clean up memory of unnecessary things (Kernerl 2.6.16 or newer)
run sync first to flush useful things out to disk!!! To free pagecache: echo 1 > /proc/sys/vm/drop_caches To free dentries and inodes: echo 2 > /proc/sys/vm/drop_caches To free pagecache, dentries and inodes: echo 3 > /proc/sys/vm/drop_caches

Using mplayer to play the audio only but suppress the video

Create package dependency graph
Create Debian package dependency graph using GraphViz


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