maint: Clarify ambiguous refs to Linux kernels or GNU/Linux systems

* README-prereq: s_linux_GNU/Linux_ or s_linux_Linux kernel_
* README-valgrind: ditto
* src/chown-core.c: ditto
* src/dd.c: ditto
* src/df.c: ditto
* src/ls.c: ditto
* src/mv.c: ditto
* src/pwd.c: ditto
* src/remove.c: ditto
* src/shred.c: ditto
* src/stat.c: ditto
* src/su.c: ditto
* src/system.h: ditto
* src/timeout.c: ditto
* src/truncate.c: ditto

README-prereq

@@ -1,12 +1,12 @@
 Detailed below are concrete examples for
 getting the prerequisites for particular systems.
 
-- linux - fedora
+- GNU/Linux - fedora
 
   This shows the steps for getting the required tools to build coreutils 7.0
   on a Fedora 8 system. We try to use official packages where possible.
   The 3 methods described for making these required packages available, should
-  help clarify build requirements on any linux system at least.
+  help clarify build requirements on any GNU/Linux system at least.
 
   1. Make sure offical distro git package is installed
     # yum install git

README-valgrind

@@ -23,7 +23,7 @@
 # find tests -name Makefile.am|xargs grep -wl PATH|xargs perl -pi -e 's,src/vg,src,'
 #
 # Create this symlink for suppressions (this is no longer necessary,
-# with linux-2.6.9 and valgrind-2.2.0):
+# with Linux kernel 2.6.9 and valgrind-2.2.0):
 # ln -s $PWD/.vg-suppressions /tmp/cu-vg
 
 # Create src/vg:

src/chown-core.c

@@ -422,7 +422,7 @@ change_file_owner (FTS *fts, FTSENT *ent,
 	    }
 	}
 
-      /* On some systems (e.g., Linux-2.4.x),
+      /* On some systems (e.g., GNU/Linux 2.4.x),
 	 the chown function resets the `special' permission bits.
 	 Do *not* restore those bits;  doing so would open a window in
 	 which a malicious user, M, could subvert a chown command run

src/dd.c

@@ -850,7 +850,7 @@ iwrite (int fd, char const *buf, size_t size)
       else if (nwritten == 0)
 	{
 	  /* Some buggy drivers return 0 when one tries to write beyond
-	     a device's end.  (Example: Linux 1.2.13 on /dev/fd0.)
+	     a device's end.  (Example: Linux kernel 1.2.13 on /dev/fd0.)
 	     Set errno to ENOSPC so they get a sensible diagnostic.  */
 	  errno = ENOSPC;
 	  break;
@@ -1201,7 +1201,7 @@ advance_input_offset (uintmax_t offset)
    to indicate that lseek failed.
 
    The offending behavior has been confirmed with an Exabyte SCSI tape
-   drive accessed via /dev/nst0 on both Linux-2.2.17 and Linux-2.4.16.  */
+   drive accessed via /dev/nst0 on both Linux 2.2.17 and 2.4.16 kernels.  */
 
 #ifdef __linux__
 
@@ -1565,7 +1565,7 @@ dd_copy (void)
      the input buffer;  thus we allocate 2 pages of slop in the
      real buffer.  8k above the blocksize shouldn't bother anyone.
 
-     The page alignment is necessary on any linux system that supports
+     The page alignment is necessary on any Linux kernel that supports
      either the SGI raw I/O patch or Steven Tweedies raw I/O patch.
      It is necessary when accessing raw (i.e. character special) disk
      devices on Unixware or other SVR4-derived system.  */
@@ -1887,7 +1887,7 @@ main (int argc, char **argv)
 	      /* Complain only when ftruncate fails on a regular file, a
 		 directory, or a shared memory object, as POSIX 1003.1-2004
 		 specifies ftruncate's behavior only for these file types.
-		 For example, do not complain when Linux 2.4 ftruncate
+		 For example, do not complain when Linux kernel 2.4 ftruncate
 		 fails on /dev/fd0.  */
 	      int ftruncate_errno = errno;
 	      struct stat stdout_stat;

src/df.c

@@ -70,7 +70,7 @@ static bool file_systems_processed;
 /* If true, invoke the `sync' system call before getting any usage data.
    Using this option can make df very slow, especially with many or very
    busy disks.  Note that this may make a difference on some systems --
-   SunOS 4.1.3, for one.  It is *not* necessary on Linux.  */
+   SunOS 4.1.3, for one.  It is *not* necessary on GNU/Linux.  */
 static bool require_sync;
 
 /* Desired exit status.  */

src/ls.c

@@ -3387,7 +3387,7 @@ print_current_files (void)
 }
 
 /* Replace the first %b with precomputed aligned month names.
-   Note on glibc-2.7 on linux at least this speeds up the whole `ls -lU`
+   Note on glibc-2.7 at least, this speeds up the whole `ls -lU`
    process by around 17%, compared to letting strftime() handle the %b.  */
 
 static size_t

src/mv.c

@@ -243,9 +243,9 @@ movefile (char *source, char *dest, bool dest_is_dir,
 
   /* This code was introduced to handle the ambiguity in the semantics
      of mv that is induced by the varying semantics of the rename function.
-     Some systems (e.g., Linux) have a rename function that honors a
+     Some systems (e.g., GNU/Linux) have a rename function that honors a
      trailing slash, while others (like Solaris 5,6,7) have a rename
-     function that ignores a trailing slash.  I believe the Linux
+     function that ignores a trailing slash.  I believe the GNU/Linux
      rename semantics are POSIX and susv2 compliant.  */
 
   if (remove_trailing_slashes)

src/pwd.c

@@ -244,7 +244,7 @@ find_dir_entry (struct stat *dot_sb, struct file_name *file_name,
    The getcwd function performs nearly the same task, but is typically
    unable to handle names longer than PATH_MAX.  This function has
    no such limitation.  However, this function *can* fail due to
-   permission problems or a lack of memory, while Linux's getcwd
+   permission problems or a lack of memory, while GNU/Linux's getcwd
    function works regardless of restricted permissions on parent
    directories.  Upon failure, give a diagnostic and exit nonzero.
 

src/remove.c

@@ -1125,9 +1125,9 @@ remove_entry (int fd_cwd, Dirstack_state const *ds, char const *filename,
 
       DO_UNLINK (fd_cwd, filename, x);
 
-      /* Upon a failed attempt to unlink a directory, most non-Linux systems
-	 set errno to the POSIX-required value EPERM.  In that case, change
-	 errno to EISDIR so that we emit a better diagnostic.  */
+      /* Upon a failed attempt to unlink a directory, most non GNU/Linux
+	 systems set errno to the POSIX-required value EPERM.  In that case,
+	 change errno to EISDIR so that we emit a better diagnostic.  */
       if (! x->recursive && errno == EPERM && is_dir_lstat (fd_cwd,
 							    filename, st))
 	errno = EISDIR;

src/shred.c

@@ -450,8 +450,8 @@ dopass (int fd, char const *qname, off_t *sizep, int type,
 
 		  /* If the first write of the first pass for a given file
 		     has just failed with EINVAL, turn off direct mode I/O
-		     and try again.  This works around a bug in linux-2.4
-		     whereby opening with O_DIRECT would succeed for some
+		     and try again.  This works around a bug in Linux kernel
+		     2.4 whereby opening with O_DIRECT would succeed for some
 		     file system types (e.g., ext3), but any attempt to
 		     access a file through the resulting descriptor would
 		     fail with EINVAL.  */

src/stat.c

@@ -184,7 +184,7 @@ static char const *trailing_delim = "";
    Some systems have statfvs.f_basetype[FSTYPSZ] (AIX, HP-UX, and Solaris).
    Others have statvfs.f_fstypename[_VFS_NAMELEN] (NetBSD 3.0).
    Others have statfs.f_fstypename[MFSNAMELEN] (NetBSD 1.5.2).
-   Still others have neither and have to get by with f_type (Linux).
+   Still others have neither and have to get by with f_type (GNU/Linux).
    But f_type may only exist in statfs (Cygwin).  */
 static char const *
 human_fstype (STRUCT_STATVFS const *statfsbuf)

src/su.c

@@ -471,7 +471,7 @@ main (int argc, char **argv)
     error (EXIT_FAILURE, 0, _("user %s does not exist"), new_user);
 
   /* Make a copy of the password information and point pw at the local
-     copy instead.  Otherwise, some systems (e.g. Linux) would clobber
+     copy instead.  Otherwise, some systems (e.g. GNU/Linux) would clobber
      the static data through the getlogin call from log_su.
      Also, make sure pw->pw_shell is a nonempty string.
      It may be NULL when NEW_USER is a username that is retrieved via NIS (YP),

src/system.h

@@ -683,7 +683,7 @@ bad_cast (char const *s)
 
    Note that this is to minimize system call overhead.
    Other values may be appropriate to minimize file system
-   or disk overhead.  For example on my current linux system
+   or disk overhead.  For example on my current GNU/Linux system
    the readahead setting is 128KiB which was read using:
 
    file="."

src/timeout.c

@@ -73,7 +73,7 @@
 
 #define AUTHORS proper_name_utf8 ("Padraig Brady", "P\303\241draig Brady")
 
-/* Note ETIMEDOUT is 110 on linux but this is non standard */
+/* Note ETIMEDOUT is 110 on GNU/Linux systems but this is non standard */
 #define EXIT_TIMEDOUT 124
 
 /* Internal failure.  */
@@ -311,11 +311,11 @@ main (int argc, char **argv)
       alarm (timeout);
 
       /* We're just waiting for a single process here, so wait() suffices.
-         Note the signal() calls above on linux and BSD at least, essentially
-         call the lower level sigaction() with the SA_RESTART flag set, which
-         ensures the following wait call will only return if the child exits,
-         not on this process receiving a signal. Also we're not passing
-         WUNTRACED | WCONTINUED to a waitpid() call and so will not get
+         Note the signal() calls above on GNU/Linux and BSD at least,
+         essentially call the lower level sigaction() with the SA_RESTART flag
+         set, which ensures the following wait call will only return if the
+         child exits, not on this process receiving a signal. Also we're not
+         passing WUNTRACED | WCONTINUED to a waitpid() call and so will not get
          indication that the child has stopped or continued.  */
       wait (&status);
 

src/truncate.c

@@ -229,7 +229,7 @@ do_ftruncate (int fd, char const *fname, off_t ssize, rel_mode_t rel_mode)
       /* Complain only when ftruncate fails on a regular file, a
          directory, or a shared memory object, as POSIX 1003.1-2004
          specifies ftruncate's behavior only for these file types.
-         For example, do not complain when Linux 2.4 ftruncate
+         For example, do not complain when Linux kernel 2.4 ftruncate
          fails on /dev/fd0.  */
       int const ftruncate_errno = errno;
       if (fstat (fd, &sb) != 0)

tests/dd/skip-seek-past-file

@@ -84,7 +84,7 @@ if ! truncate --size=$OFF_T_MAX in 2>/dev/null; then
     # so just check for the skip warning.
     compare skip_err err || fail=1
   else
-    # On Linux at least lseek(>max file size) fails.
+    # On Linux kernels at least, lseek(>max file size) fails.
     # error message should be "... cannot skip: strerror(EINVAL)"
     grep "cannot skip:" err >/dev/null || fail=1
   fi