Make some small improvements to the magic man page, including nesting

the list of magic line elements correctly, modernising some of the
early discussion of magic patterns, and making the warning against
regexs clearer.

diff --git a/doc/magic.man b/doc/magic.man
index d8466ba9418ebc1dcfc1639e6608b47a06580953..56efe6c5b62a018bb247ef6fc90ade9d923ebc54 100644 (file)
--- a/doc/magic.man
+++ b/doc/magic.man
@@ -1,4 +1,4 @@
-.\" $File: magic.man,v 1.51 2008/02/18 18:32:31 rrt Exp $
+.\" $File: magic.man,v 1.52 2008/02/28 13:14:26 rrt Exp $
 .Dd January 10, 2007
 .Dt MAGIC __FSECTION__
 .Os
@@ -25,8 +25,7 @@ and additional information to extract from the file.
 .Pp
 Each line of the file specifies a test to be performed.
 A test compares the data starting at a particular offset
-in the file with a 1-byte, 2-byte, or 4-byte numeric value or
-a string.
+in the file with a byte value, a string or a numeric value.
 If the test succeeds, a message is printed.
 The line consists of the following fields:
 .Bl -tag -width ".Dv message"
@@ -148,10 +147,11 @@ interpreted as a UNIX-style date, but interpreted as local time rather
 than UTC.
 .It Dv regex
 A regular expression match in extended POSIX regular expression syntax
-(much like egrep). Regular expressions can easily take exponential
-time to process; their use is discouraged. When used in production
-environments, their performance should be carefully checked. The type
-specification can be optionally followed by
+(like egrep). Regular expressions can take exponential time to
+process, and their performance is hard to predict, so their use is
+discouraged. When used in production environments, their performance
+should be carefully checked. The type specification can be optionally
+followed by
 .Dv /[c][s] .
 The
 .Dq c
@@ -186,7 +186,6 @@ This is intended to be used with the test
 (which is always true) and a message that is to be used if there are
 no other matches.
 .El
-.El
 .Pp
 The numeric types may optionally be followed by
 .Dv \*[Am]
@@ -196,7 +195,6 @@ numeric value before any comparisons are done.
 Prepending a
 .Dv u
 to the type indicates that ordered comparisons should be unsigned.
-.Bl -tag -width ".Dv message"
 .It Dv test
 The value to be compared with the value from the file.
 If the type is
@@ -360,11 +358,11 @@ That way variable length structures can be examined:
 \*[Gt]\*[Gt](0x3c.l)  string  LX\e0\e0  LX executable (OS/2)
 .Ed
 .Pp
-This strategy of examining has one drawback: You must make sure that
+This strategy of examining has a drawback: You must make sure that
 you eventually print something, or users may get empty output (like, when
 there is neither PE\e0\e0 nor LE\e0\e0 in the above example)
 .Pp
-If this indirect offset cannot be used as-is, there are simple calculations
+If this indirect offset cannot be used directly, simple calculations are
 possible: appending
 .Em [+-*/%\*[Am]|^]number
 inside parentheses allows one to modify
@@ -478,4 +476,4 @@ a system on which the lengths are invariant.
 .\" the changes I posted to the S5R2 version.
 .\"
 .\" Modified for Ian Darwin's version of the file command.
-.\" @(#)$Id: magic.man,v 1.52 2008/02/28 13:14:26 rrt Exp $
+.\" @(#)$Id: magic.man,v 1.53 2008/02/28 20:10:10 rrt Exp $