cheat sheets.

--- bash version 21	Fri Jun 13 19:12:44 +0000 2008
+++ bash version 22	Fri Jun 13 23:21:20 +0000 2008
@@ -1,85 +1,88 @@
-  !! - Last command
+!! - Last command
   !foo - Run most recent command starting with 'foo...' (ex. !ps, !mysqladmin)
   !foo:p - Print command that !foo would run, and add it as the latest to
   command history
   !$ - Last 'word' of last command ('/path/to/file' in the command 'ls -lAFh
   /path/to/file', '-uroot' in 'mysql -uroot')
   !$:p - Print word that !$ would substitute
   !* - All but first word of last command ('-lAFh /path/to/file' in the command
   'ls -lAFh /path/to/file', '-uroot' in 'mysql -uroot')
   !*:p - Print words that !* would substitute
 
   ^foo^bar - Replace 'foo' in last command with 'bar', print the result, then
   run. ('mysqladmni -uroot', run '^ni^in', results in 'mysqladmin -uroot')
 
   {a,b,c} passes words to the command, substituting a, b, and c sequentially
   (`cp file{.bk}` runs `cp file file.bk`)
 
   Ctrl + a - Jump to the start of the line
   Ctrl + b - Move back a char
   Ctrl + c - Terminate the command
   Ctrl + d - Delete from under the cursor
   Ctrl + e - Jump to the end of the line
   Ctrl + f - Move forward a char
   Ctrl + k - Delete to EOL
   Ctrl + l - Clear the screen
   Ctrl + r - Search the history backwards
   Ctrl + R - Search the history backwards with multi occurrence
   Ctrl + t - Transpose the current char with the previous
   Ctrl + u - Delete backward from cursor
   Ctrl + w - Delete backward a word
   Ctrl + xx - Move between EOL and current cursor position
   Ctrl + x @ - Show possible hostname completions
   Ctrl + z - Suspend/ Stop the command
 
   Alt + < - Move to the first line in the history
   Alt + > - Move to the last line in the history
   Alt + ? - Show current completion list
   Alt + * - Insert all possible completions
   Alt + / - Attempt to complete filename
   Alt + . - Yank last argument to previous command
   Alt + b - Move backward
   Alt + c - Capitalize the word
   Alt + d - Delete word
   Alt + f - Move forward
   Alt + l - Make word lowercase
   Alt + n - Search the history forwards non-incremental
   Alt + p - Search the history backwards non-incremental
   Alt + r - Recall command
   Alt + t - Transpose the current word with the previous
   Alt + u - Make word uppercase
   Alt + back-space - Delete backward from cursor
 
   (Here "2T" means Press TAB twice)
   $ 2T - All available commands(common)
   $ (string)2T - All available commands starting with (string)
   $ /2T - Entire directory structure including Hidden one
   $ (dir)2T - Only Sub Dirs inside (dir) including Hidden one
   $ *2T - Only Sub Dirs inside without Hidden one 
   $ ~2T - All Present Users on system from "/etc/passwd"
   $ $2T - All Sys variables
   $ @2T - Entries from "/etc/hosts"
   $ =2T - Output like ls or dir
   .bash_profile = sourced by login shell, 
   .bashrc = sourced by all shells, 
   .bash_aliases = should be sourced by .bashrc
 
 Run something:
   for i in a b c; do $i 'hello'; done
 
 Do something on a bunch of files:
   for i in *.rb; do echo $i; done
 
 If syntax:
   if [ -e .ssh ]; then echo "hi"; fi
 
 file check flags:
   -e:  file exists
   -f:  regular file (non directory)
   -d:  directory
   -s:  non-zero file
   -x:  execute permission
+
+Avoid duplicates in your history:
+  export HISTIGNORE=&quot;&amp;:ls:ls *:[bf]g:exit&quot;
 
 more here:
   http://www.linuxtopia.org/online_books/advanced_bash_scripting_guide/fto.html