Differences

This shows you the differences between two versions of the page.

--- fuss:sh [2018/04/06 23:56] – [Copyright] office
+++ fuss:sh [2019/11/08 16:40] – [Scramble a String] office
@@ Line 751: / Line 751: @@
 The following command will generate an alpha-numeric string from the real random number device that would be suitable to be used as a password:
 <code bash>
-grep -m 10 -ao '[[:alnum:]]' < /dev/urandom | xargs | tr -d ' '
+egrep -m 10 -ao '[\x20-\x7E]{1}$' </dev/random | tr -d '\n' | wc -c
 </code>
 where:
-  * ''-m 10'' matches $10$ alpha-numeric characters (''<nowiki>[[:alnum:]]</nowiki>'') from ''/dev/urandom'',
+  * ''-m 10'' matches $10$ printable characters (all ASCII characters starting from space ''20'' octal and up to tilde symbol ''7E'' in octal) from ''/dev/urandom'',
   * ''-a'' instructs grep to treat even binary input as characters,
   * ''-o'' instructs grep to only print matches,
-  * ''<nowiki>[[:alnum:]]</nowiki>'' only matches alpha-numeric characters (this could be a regular expression instead of using GNU bracketed expressions),
+  * ''tr'' will be used to delete space characters, and
-  * ''xargs'' will pass the $10$ extracted alpha-numeric characters as parameters to the next command on the pipe,
+  * ''wc -c'' will count the characters for verification.
-  * ''tr'' will be used to delete space characters
+On OSX you can prevent the password to be echoed to the terminal by enqueueing the ''pbcopy'' command, ie:
+<code bash>
+egrep -m 20 -ao '[\x20-\x7E]{1}$' </dev/random | tr -d '\n' | pbcopy
+</code>
+which will then place the password in the clipboard.
 ====== Detach, Background and Re-Attach a Process ======
@@ Line 779: / Line 784: @@
 Later on, to check up on the command's progress, issue the command ''tmux attach''.
+====== Scramble a String ======
+<code bash>
+echo 'AGsg4SKKs74s62#' | sed 's/./&\n/g' | shuf | tr -d "\n"
+</code>
+====== Generate Random Numbers in Range using awk ======
+<code bash>
+awk -v min=X -v max=Y 'BEGIN{srand(); print int(min+rand()*(max-min+1))}'
+</code>
+where:
+  * ''X'' is the low number,
+  * ''Y'' is the high number