ksh Special Variables

The following special variables are predefined:

$ The last argument of the previous simple command, also the pathname of the mailfile when checking for mail
$# The number of positional parameters, $1 ...
$- The set of options which were supplied at invocation
$? The return value of the last command executed, 0 to 255. If greater than 127, indicates that the command was terminated by a signal. The signal number is equal to $? minus 128.
$$ The process ID of this dbx process
$! The process ID of the last background process
$* The positional parameters
$@ The positional parameters

The last two are equivalent except when quoted. $* yields one argument with the positional parameters separated by spaces. $@ yields n arguments, each quoted with "". If the positional parameters are:

hi there

foo

(that is, three parameters, one containing a space), $* is equal to

"a hi there foo"

whereas $@ is

"a" "hi there" "foo"

$	The last argument of the previous simple command, also the pathname of the mailfile when checking for mail
`$#`	The number of positional parameters, $1 ...
`$-`	The set of options which were supplied at invocation
`$?`	The return value of the last command executed, 0 to 255. If greater than 127, indicates that the command was terminated by a signal. The signal number is equal to `$?` minus 128.
`$$`	The process ID of this dbx process
`$!`	The process ID of the last background process
`$*`	The positional parameters
`$@`	The positional parameters