Consistency: "unix" ==> "\UNIX{}"

Doc/lib/libmailcap.tex

@@ -15,7 +15,7 @@ the xmpeg program can be automatically started to view the file.
 The mailcap format is documented in RFC 1524, ``A User Agent
 Configuration Mechanism For Multimedia Mail Format Information'', but
 is not an Internet standard.  However, mailcap files are supported on
-most Unix systems.
+most \UNIX{} systems.
 
 \begin{funcdesc}{findmatch}{caps\, MIMEtype\, key\, filename\, plist}
 Return a 2-tuple; the first element is a string containing the command

Doc/lib/librotor.tex

@@ -99,8 +99,7 @@ The version implemented here is probably a good deal more difficult to crack
 a truly skilful and determined attacker to break the cipher.  So if you want
 to keep the NSA out of your files, this rotor cipher may well be unsafe, but
 for discouraging casual snooping through your files, it will probably be
-just fine, and may be somewhat safer than using the Unix \file{crypt}
+just fine, and may be somewhat safer than using the \UNIX{} \file{crypt}
 command.
 \index{National Security Agency}\index{crypt(1)}
 % XXX How were Unix commands represented in the docs?
-

Doc/libmailcap.tex

@@ -15,7 +15,7 @@ the xmpeg program can be automatically started to view the file.
 The mailcap format is documented in RFC 1524, ``A User Agent
 Configuration Mechanism For Multimedia Mail Format Information'', but
 is not an Internet standard.  However, mailcap files are supported on
-most Unix systems.
+most \UNIX{} systems.
 
 \begin{funcdesc}{findmatch}{caps\, MIMEtype\, key\, filename\, plist}
 Return a 2-tuple; the first element is a string containing the command

Doc/librotor.tex

@@ -99,8 +99,7 @@ The version implemented here is probably a good deal more difficult to crack
 a truly skilful and determined attacker to break the cipher.  So if you want
 to keep the NSA out of your files, this rotor cipher may well be unsafe, but
 for discouraging casual snooping through your files, it will probably be
-just fine, and may be somewhat safer than using the Unix \file{crypt}
+just fine, and may be somewhat safer than using the \UNIX{} \file{crypt}
 command.
 \index{National Security Agency}\index{crypt(1)}
 % XXX How were Unix commands represented in the docs?
-