Bash-Beginners-Guide

Bash Guide for Beginners
cheesecloth
cheetah
--output omitted--
If you want to find the literal asterisk character in a file or output, use single quotes. Cathy in the example
below first tries finding the asterisk character in /etc/profile without using quotes, which does not
return any lines. Using quotes, output is generated:
cathy ~> grep * /etc/profile
cathy ~> grep '*' /etc/profile
for i in /etc/profile.d/*.sh ; do
4.3. Pattern matching using Bash features
4.3.1. Character ranges
Apart from grep and regular expressions, there's a good deal of pattern matching that you can do directly in
the shell, without having to use an external program.
As you already know, the asterisk (*) and the question mark (?) match any string or any single character,
respectively. Quote these special characters to match them literally:
cathy ~> touch "*"
cathy ~> ls "*"
*
But you can also use the square braces to match any enclosed character or range of characters, if pairs of
characters are separated by a hyphen. An example:
cathy ~> ls -ld [a-cx-z]*
drwxr-xr-x 2 cathy cathy 4096 Jul 20 2002 app-defaults/
drwxrwxr-x 4 cathy cathy 4096 May 25 2002 arabic/
drwxrwxr-x 2 cathy cathy 4096 Mar 4 18:30 bin/
drwxr-xr-x 7 cathy cathy 4096 Sep 2 2001 crossover/
drwxrwxr-x 3 cathy cathy 4096 Mar 22 2002 xml/
This lists all files in cathy's home directory, starting with "a", "b", "c", "x", "y" or "z".
If the first character within the braces is "!" or "^", any character not enclosed will be matched. To match the
dash ("-"), include it as the first or last character in the set. The sorting depends on the current locale and of
the value of the LC_COLLATE variable, if it is set. Mind that other locales might interpret "[a-cx-z]" as
"[aBbCcXxYyZz]" if sorting is done in dictionary order. If you want to be sure to have the traditional
interpretation of ranges, force this behavior by setting LC_COLLATE or LC_ALL to "C".
4.3.2. Character classes
Character classes can be specified within the square braces, using the syntax [:CLASS:], where CLASS is
defined in the POSIX standard and has one of the values
"alnum", "alpha", "ascii", "blank", "cntrl", "digit", "graph", "lower", "print", "punct", "space", "upper", "word"
or "xdigit".
Some examples:
Chapter 4. Regular expressions 60