Overview of Common Unix - Shell Features

Overview of common shell features. The following features are standard in every shell. List is as follows -
Command Meaning
> Redirect output
>> Append to file
< Redirect input
<< "Here" document (redirect input)
| Pipe output
& Run process in background.
; Separate commands on same line
* Match any character(s) in filename
? Match single character in filename
[ ] Match any characters enclosed
( ) Execute in subshell
` ` Substitute output of enclosed command
" " Partial quote (allows variable and command expansion)
' ' Full quote (no expansion)
\ Quote following character
$var Use value for variable
$$ Process id
$0 Command name
$n nth argument (n from 0 to 9)
$* All arguments as a simple word
# Begin comment
bg Background execution
break Break from loop statements
cd Change directories
continue Resume a program loop
echo Display output
eval Evaluate arguments
exec Execute a new shell