/dev/urandom relies on operator input to set the random seed. By itself, this may not contain enough random bits to produce high entropy output, especially if the system was recently restarted. Therefore, key stretching through a hash reduces the risk of using low-entropy output as a security key.

Generate a 18 character password from character set a-zA-Z0-9 from /dev/urandom, pipe the output to Python which prints the password on standard out and in crypt sha512 form.

/dev/urandom relies on operator input to set the random seed. By itself, this may not contain enough random bits to produce high entropy output, especially if the system was recently restarted. Therefore, key stretching through a hash reduces the risk of using low-entropy output as a security key.

This command will encode a string using the ROT47 cipher.

Lauching an app including jars in an adjacent lib folder to its classpath

Also shows files as they are found. Only works from a tty.

Copying and pasting from Office documents open in Office:mac can dirty your files with Windows CRLF and (inexplicably) Classic Mac OS LF newlines, which can break some tools. This snippet replaces them with good ol' Unix LF newlines.

If there are spaces won't work.

Convert long list of ' ' to a single space. Compress space and other characters.

Translates first set into second set

All files in the directory will be renamed replacing every space in the filename by "_" (underline) and converting upper case characters to lower case characters.

e.g. Foo Bar.txt --> foo_bar.txt

Use tput cols to find the width of the terminal and set it as the minimum field width.

dd can be used with /dev/zero to easily create a file of all zero-bytes. Pipe that through tr and use octal conversions to change the byte values from zero to 0xff (octal 0377). You can replace 0377 with the byte of your choice. You can also use \\0 and \\377 instead of the quoted version.

Returns last day of current month. Useful to implement a bash script backup based on a GFS strategy.

usage: dng BRE [selection]

default selection is the last match

DNS is ok, but although domainnames may be easier to remember than IP numbers, it still requires typing them out. This can be error-prone. Even more so than typing IPv4 numbers, depending on the domainname, its length and complexity.