Linux Shells by Example

10.9. Special Variables and Modifiers

Built into the TC shell are several variables consisting of one character. The $ preceding the character allows variable interpretation. See Table 10.21.

Table 10.21. Variables and Their Meanings

Variable	Example	Meaning
$?var	echo $?name	Returns 1 if variable has been set, 0 if not.
$#var	echo $#fruit	Prints the number of elements in an array.
$%var	echo $%name	Prints number of characters in a variable or array.
$$	echo $$	Prints the PID of the current shell.
$<	set name = $<	Accepts a line of input from user up to newline.
$?	echo $?	Same as $status. Contains the exit status of the last command.
$!	kill $!	Contains the process id number of the last job put in the background.

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