Commands by renich (10)

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Recursive find and replace file extension / suffix (mass rename files)
Find recursively all files in ~/Notes with the extension '.md' and pipe that via xargs to rename command, which will replace every '.md' to '.txt' in this example (existing files will not be overwritten).

Compare two directory trees.
This uses Bash's "process substitution" feature to compare (using diff) the output of two different process pipelines.

Compress blank lines

Create a random file of a certain, and display progress along the way.
SIZE is the number of gigabytes and the file name is at the end. Random data is generated by encrypting /dev/zero, similar to other techniques posted on here.

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"

What is My WAN IP?
The curl command retrieve the HTML text containing the IP address. The grep command picks out the IP address from that HTML text.

Sort IP addresses
Sort IP address by order

split large video file
i have a large video file, 500+ MB, so i cant upload it to flickr, so to reduce the size i split it into 2 files. the command shows the splitting for the first file, from 0-4 minutes. ss is start time and t is duration (how long you want the output file to be). credit goes to philc: http://ubuntuforums.org/showthread.php?t=480343 NOTE: when i made the second half of the video, i got a *lot* of lines like this: frame= 0 fps= 0 q=0.0 size= 0kB time=10000000000.00 bitrate= 0.0kbit just be patient, it is working =)

Mount a .iso file in UNIX/Linux
"-o loop" lets you use a file as a block device

Get last sleep time on a Mac
Similarly for last wake time: $ sysctl -a | grep waketime


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