Wild Cards in Linux - Every Beginner should know_weixin

Hello, techies!

Welcome to my article on Linux wildcards, wildcards are symbols or set of symbols used to substitute in place of a character or characters for the pattern match in a string.

Wildcard	Description
?	denote single character
????	to specify number of character of that filename size
*	every thing or all
[]	represent range
ls m[a-d]n	file start with m and end with n having charcter including a to d
*{.doc,.pdf}*	match all doc file and pdf file
[!9]	ignore 9 or don't match 9
\	string literal skip
touch \	to create a file name \
$1, $2, $3, ...	are the positional parameters
"$@"	is an array-like construct of all positional parameters, {$1, $2, $3 ...}
*"$"**	is the IFS expansion of all positional parameters, $1 $2 $3 ....
$#	is the number of positional parameters
$-	current options set for the shell
$$	PID of the current shell (not subshell)
$IFS	is the (input) field separator
$?	is the most recent foreground pipeline exit status
$!	is the PID of the most recent background command
$0	is the name of the shell or shell script
$_	most recent parameter (or the abs path of the command to start the current shell immediately after startup)