Commands using echo (1,545)

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Generate random valid mac addresses
First set the variable $hexchars: $hexchars="0123456789ABCDEF" Change the number in the first for loop if you need less then 1200 mac addresses

A DESTRUCTIVE command to render a drive unbootable
Overwrites the boot sector. Since this doesn't overwrite any data, you can usually recover by re-creating the partition table exactly the same as before you zeroed it. This can also help sometimes if you install a new drive in a Windows machine which can't read it.

edit, view or execute last modified file with a single key-press
Copy this function to command line, press 'Enter' 'f'' 'Enter' to execute (sentence on the left written only for newbies). Hint 'e|x|v|1..9' in front of displayed last modified file name means: "Press 'e' for edit,'x' for execute,'v' for view or a digit-key '1..9' to touch one file from the recent files list to be last modified" and suggested (hidden files are listed too, else remove 'a' from 'ls -tarp' statement if not intended). If you find this function useful you can then rename it if needed and append or include into your ~/.bashrc config script. With the command $ . ~/.bashrc the function then can be made immediately available. In the body of the function modifications can be made, i.e. replaced joe editor command or added new option into case statement, for example 'o) exo-open $h;;' command for opening file with default application - or something else (here could not be added since the function would exceed 255 chars). To cancel execution of function started is no need to press Ctrl-C - if the mind changed and want to leave simple Enter-press is enough. Once defined, this function can with $ typeset -f f command be displayed in easy readable form

Downmix from stereo to mono and play radio stream with mplayer
The solution to a year long (and extremely frustrating) problem I've had, caused by the fact that I only have one speaker; this command downmixes the stream to monophonic output, making sure I don't miss any of the music. NOTE: When stream is in .m3u format, a -playlist option is required, as shown below: $ mplayer -af pan=1:0.5:0.5 -channels 1 -playlist radiostream.m3u This command works great with aliases for various channels in .bashrc. Sample below: $ alias radio1='mplayer -af pan=1:0.5:0.5 -channels 1 radio1stream.pls'

simple du command to give size of next level of subfolder in MB
If you're only using -m or -k, you will need to remember they are either in Megabyte or kilobyte forms. So by using -B, it gives you the unit of the size measurement, which helps you from reading the result faster. You can try with -B K as well.

Recall “N”th command from your BASH history without executing it.

a find and replace within text-based files, to locate and rewrite text en mass.
syntax follows regular command line expression. example: let's say you have a directory (with subdirs) that has say 4000 .php files. All of these files were made via script, but uh-oh, there was a typo! if the typo is "let's go jome!" but you meant it to say "let's go home!" find . -name "*.php" | xargs perl -pi -e "s/let\'s\ go\ jome\!/let\'s\ go\ home\!/g" all better :) multiline: find . -name "*.php" | xargs perl -p0777i -e 's/knownline1\nknownline2/replaced/m' indescriminate line replace: find ./ -name '*.php' | xargs perl -pi -e 's/\".*$\"/\new\ line\ content/g'

Gets the english pronunciation of a phrase
Sends a string to google tranlator, which converts it to English speech. It's possible to create a nice script to do the job for us, such as #!/bin'bash curl -A "Mozilla" "http://translate.google.com/translate_tts?tl=en&q=$1" > /tmp/speak.mp3 mplayer /tmp/speak.mp3

cd to (or operate on) a file across parallel directories
This is useful for quickly jumping around branches in a file system, or operating on a parellel file. This is tested in bash. cd to (substitute in PWD, a for b) where PWD is the bash environmental variable for the "working directory"

Edit all files found having a specific string found by grep
The grep switches eliminate the need for awk and sed. Modifying vim with -p will show all files in separate tabs, -o in separate vim windows. Just wish it didn't hose my terminal once I exit vim!!


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