35.11. Pattern Matching in case Statements
A case statement (Section 35.10) is good at
string pattern matching. Its
metacharacters work like the filename
wildcards (Section 1.13) in the shell,
with a few twists. Here are some examples:
string with exactly one character like a,
3, !, and so on.
Matches a string with one or more
characters (a nonempty string).
y, Y or yes,
YES, YeS, etc. The
| means "or."
Matches a file pathname, like
/xxx/yyy/somedir/file2, that starts with a
slash, contains at least one more slash, and ends with a digit.
- 'What now?')
the pattern What now?. The quotes (Section 27.12) tell the
shell to treat the string literally: not to break it at the space and
not to treat the ? as a wildcard.
the contents of the msgs variable. The double
quotes let the shell substitute the variable's
value; the quotes also protect spaces and other special characters
from the shell. For example, if msgs contains
first next, this would match the same string,
To clarify: in bash, for example, the
case statement uses the same pathname expansion
rules it uses elsewhere in the shell, to determine how to expand the
value. In other shells, such as ksh, there are
minor differences (such as a relaxation of special treatment for .
and / characters). See the manual page for your
shell if you have any questions or concerns about what rules your
shell will follow.
--JP and SJC
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