Various pages: Standardize wording around setting of 'errno' on error

In the RETURN VALUE sections, a number of different wordings
are used in to describe the fact that 'errno' is set on error.
There's no reason for the difference in wordings, since the same
thing is being described in each case. Switch to a standard
wording that is the same as FreeBSD and similar to the wording
used in POSIX.1.

In this change, "to indicate the cause of the error"
is changed to "to indicate the error".

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man2/add_key.2

@@ -147,7 +147,7 @@ On success,
 returns the serial number of the key it created or updated.
 On error, \-1 is returned and
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 .SH ERRORS
 .TP
 .B EACCES

man2/futex.2

@@ -1320,7 +1320,7 @@ was invoked via
 .BR syscall (2)),
 all operations return \-1 and set
 .I errno
-to indicate the cause of the error.
+to indicate the error.
 .PP
 The return value on success depends on the operation,
 as described in the following list:

man2/getpriority.2

@@ -123,7 +123,7 @@ On success,
 returns the calling thread's nice value, which may be a negative number.
 On error, it returns \-1 and sets
 .I errno
-to indicate the cause of the error.
+to indicate the error.
 .PP
 Since a successful call to
 .BR getpriority ()

man2/inotify_rm_watch.2

@@ -53,7 +53,7 @@ On success,
 returns zero.
 On error, \-1 is returned and
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 .SH ERRORS
 .TP
 .B EBADF

man2/ioctl_userfaultfd.2

@@ -235,7 +235,7 @@ This
 operation returns 0 on success.
 On error, \-1 is returned and
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 Possible errors include:
 .TP
 .B EFAULT
@@ -333,7 +333,7 @@ This
 operation returns 0 on success.
 On error, \-1 is returned and
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 Possible errors include:
 .\" FIXME Is the following error list correct?
 .\"
@@ -386,7 +386,7 @@ This
 operation returns 0 on success.
 On error, \-1 is returned and
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 Possible errors include:
 .TP
 .B EINVAL
@@ -466,7 +466,7 @@ operation returns 0 on success.
 In this case, the entire area was copied.
 On error, \-1 is returned and
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 Possible errors include:
 .TP
 .B EAGAIN
@@ -570,7 +570,7 @@ operation returns 0 on success.
 In this case, the entire area was zeroed.
 On error, \-1 is returned and
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 Possible errors include:
 .TP
 .B EAGAIN
@@ -636,7 +636,7 @@ This
 operation returns 0 on success.
 On error, \-1 is returned and
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 Possible errors include:
 .TP
 .B EINVAL

man2/mmap.2

@@ -497,14 +497,14 @@ On error, the value
 .IR "(void\ *)\ \-1" )
 is returned, and
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 .PP
 On success,
 .BR munmap ()
 returns 0.
 On failure, it returns \-1, and
 .I errno
-is set to indicate the cause of the error (probably to
+is set to indicate the error (probably to
 .BR EINVAL ).
 .SH ERRORS
 .TP

man2/open_by_handle_at.2

@@ -282,7 +282,7 @@ returns a file descriptor (a nonnegative integer).
 .PP
 In the event of an error, both system calls return \-1 and set
 .I errno
-to indicate the cause of the error.
+to indicate the error.
 .SH ERRORS
 .BR name_to_handle_at ()
 and

man2/perfmonctl.2

@@ -193,7 +193,7 @@ Reset PMC registers to default values.
 returns zero when the operation is successful.
 On error, \-1 is returned and
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 .SH VERSIONS
 .BR perfmonctl ()
 is available since Linux 2.4.

man2/pidfd_getfd.2

@@ -74,7 +74,7 @@ On success,
 returns a file descriptor (a nonnegative integer).
 On error, \-1 is returned and
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 .SH ERRORS
 .TP
 .B EBADF

man2/pidfd_open.2

@@ -53,7 +53,7 @@ On success,
 returns a file descriptor (a nonnegative integer).
 On error, \-1 is returned and
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 .SH ERRORS
 .TP
 .B EINVAL

man2/pidfd_send_signal.2

@@ -96,7 +96,7 @@ On success,
 returns 0.
 On error, \-1 is returned and
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 .SH ERRORS
 .TP
 .B EBADF

man2/poll.2

@@ -354,7 +354,7 @@ before any file descriptors became read.
 .PP
 On error, \-1 is returned, and
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 .SH ERRORS
 .TP
 .B EFAULT

man2/pread.2

@@ -89,7 +89,7 @@ and
 .PP
 On error, \-1 is returned and
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 .SH ERRORS
 .BR pread ()
 can fail and set

man2/readahead.2

@@ -68,7 +68,7 @@ On success,
 .BR readahead ()
 returns 0; on failure, \-1 is returned, with
 .I errno
-set to indicate the cause of the error.
+set to indicate the error.
 .SH ERRORS
 .TP
 .B EBADF

man2/request_key.2

@@ -378,7 +378,7 @@ On success,
 returns the serial number of the key it found or caused to be created.
 On error, \-1 is returned and
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 .SH ERRORS
 .TP
 .B EACCES

man2/sched_setattr.2

@@ -303,7 +303,7 @@ and
 return 0.
 On error, \-1 is returned, and
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 .SH ERRORS
 .BR sched_getattr ()
 and

man2/seccomp.2

@@ -727,7 +727,7 @@ and
 .BR gettid (2).)
 On other errors, \-1 is returned, and
 .IR errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 .SH ERRORS
 .BR seccomp ()
 can fail for the following reasons:

man2/shmop.2

@@ -170,13 +170,13 @@ returns the address of the attached shared memory segment; on error,
 .I (void\ *)\ \-1
 is returned, and
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 .PP
 On success,
 .BR shmdt ()
 returns 0; on error \-1 is returned, and
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 .SH ERRORS
 When
 .BR shmat ()

man2/sysinfo.2

@@ -104,7 +104,7 @@ On success,
 returns zero.
 On error, \-1 is returned, and
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 .SH ERRORS
 .TP
 .B EFAULT

man2/write.2

@@ -98,7 +98,7 @@ see NOTES for the upper limit on Linux.
 .SH RETURN VALUE
 On success, the number of bytes written is returned.
 On error, \-1 is returned, and \fIerrno\fP is set
-to indicate the cause of the error.
+to indicate the error.
 .PP
 Note that a successful
 .BR write ()

man3/bindresvport.3

@@ -70,7 +70,7 @@ has no way to return the port number actually allocated.
 .BR bindresvport ()
 returns 0 on success; otherwise \-1 is returned and
 .I errno
-set to indicate the cause of the error.
+is set to indicate the error.
 .SH ERRORS
 .BR bindresvport ()
 can fail for any of the same reasons as

man3/ctime.3

@@ -311,7 +311,7 @@ returns the value
 The remaining functions return NULL on error.
 On error,
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 .SH ERRORS
 .TP
 .B EOVERFLOW

man3/dirfd.3

@@ -64,7 +64,7 @@ On success,
 returns a file descriptor (a nonnegative integer).
 On error, \-1 is returned, and
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 .SH ERRORS
 POSIX.1-2008 specifies two errors,
 neither of which is returned by the current

man3/duplocale.3

@@ -66,7 +66,7 @@ On error, it returns
 .IR "(locale_t)\ 0",
 and sets
 .I errno
-to indicate the cause of the error.
+to indicate the error.
 .SH ERRORS
 .TP
 .B ENOMEM

man3/fpathconf.3

@@ -176,7 +176,7 @@ The return value of these functions is one of the following:
 .IP * 3
 On error, \-1 is returned and
 .I errno
-is set to indicate the cause of the error
+is set to indicate the error
 (for example,
 .BR EINVAL ,
 indicating that

man3/get_phys_pages.3

@@ -47,7 +47,7 @@ On success,
 these functions return a nonnegative value as given in DESCRIPTION.
 On failure, they return \-1 and set
 .I errno
-to indicate the cause of the error.
+to indicate the error.
 .SH ERRORS
 .TP
 .B ENOSYS

man3/getlogin.3

@@ -107,7 +107,7 @@ precisely because the user can set \fBLOGNAME\fP arbitrarily.
 returns a pointer to the username when successful,
 and NULL on failure, with
 .I errno
-set to indicate the cause of the error.
+set to indicate the error.
 .BR getlogin_r ()
 returns 0 when successful, and nonzero on failure.
 .SH ERRORS

man3/getspnam.3

@@ -208,7 +208,7 @@ are available or if an error occurs during processing.
 The functions which have \fIint\fP as the return value return 0 for
 success and \-1 for failure, with
 .I errno
-set to indicate the cause of the error.
+set to indicate the error.
 .PP
 For the nonreentrant functions, the return value may point to static area,
 and may be overwritten by subsequent calls to these functions.

man3/hsearch.3

@@ -175,7 +175,7 @@ and
 return nonzero on success.
 They return 0 on error, with
 .I errno
-set to indicate the cause of the error.
+set to indicate the error.
 .PP
 On success,
 .BR hsearch ()
@@ -189,7 +189,7 @@ cannot be found in the hash table.
 returns nonzero on success, and 0 on error.
 In the event of an error, these two functions set
 .I errno
-to indicate the cause of the error.
+to indicate the error.
 .SH ERRORS
 .BR hcreate_r ()
 and

man3/inet_net_pton.3

@@ -125,7 +125,7 @@ On success,
 returns the number of bits in the network number.
 On error, it returns \-1, and
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 .PP
 On success,
 .BR inet_net_ntop ()
@@ -133,7 +133,7 @@ returns
 .IR pres .
 On error, it returns NULL, and
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 .SH ERRORS
 .TP
 .B EAFNOSUPPORT

man3/newlocale.3

@@ -181,7 +181,7 @@ returns
 .IR "(locale_t)\ 0",
 and sets
 .I errno
-to indicate the cause of the error.
+to indicate the error.
 .SH ERRORS
 .TP
 .B EINVAL

man3/posix_memalign.3

@@ -135,7 +135,7 @@ and
 .BR pvalloc ()
 return a pointer to the allocated memory on success.
 On error, NULL is returned, and \fIerrno\fP is set
-to indicate the cause of the error.
+to indicate the error.
 .PP
 .BR posix_memalign ()
 returns zero on success, or one of the error values listed in the

man3/pthread_mutex_consistent.3

@@ -58,7 +58,7 @@ On success,
 .IR pthread_mutex_consistent ()
 returns 0.
 Otherwise,
-it returns a positive error number to indicate the cause of the error.
+it returns a positive error number to indicate the error.
 .SH ERRORS
 .TP
 .B EINVAL

man3/random.3

@@ -138,7 +138,7 @@ On success,
 returns a pointer to the previous state array.
 On error, it returns NULL, with
 .I errno
-set to indicate the cause of the error.
+set to indicate the error.
 .SH ERRORS
 .TP
 .B EINVAL

man3/random_r.3

@@ -127,7 +127,7 @@ or be the result of a previous call of
 All of these functions return 0 on success.
 On error, \-1 is returned, with
 .I errno
-set to indicate the cause of the error.
+set to indicate the error.
 .SH ERRORS
 .TP
 .B EINVAL

man3/scandir.3

@@ -178,7 +178,7 @@ function returns the number of directory entries
 selected.
 On error, \-1 is returned, with
 .I errno
-set to indicate the cause of the error.
+set to indicate the error.
 .PP
 The
 .BR alphasort ()

man3/setenv.3

@@ -107,7 +107,7 @@ and
 functions return zero on success,
 or \-1 on error, with
 .I errno
-set to indicate the cause of the error.
+set to indicate the error.
 .SH ERRORS
 .TP
 .B EINVAL

man3/shm_open.3

@@ -178,7 +178,7 @@ returns 0 on success, or \-1 on error.
 .SH ERRORS
 On failure,
 .I errno
-is set to indicate the cause of the error.
+is set to indicate the error.
 Values which may appear in
 .I errno
 include the following:

man3/siginterrupt.3

@@ -77,7 +77,7 @@ signal number
 .I sig
 is invalid, with
 .I errno
-set to indicate the cause of the error.
+set to indicate the error.
 .SH ERRORS
 .TP
 .B EINVAL

man3/sigsetops.3

@@ -121,7 +121,7 @@ is not a member, and \-1 on error.
 .PP
 On error, these functions set
 .I errno
-to indicate the cause of the error.
+to indicate the error.
 .SH ERRORS
 .TP
 .B EINVAL

man3/strdup.3

@@ -109,7 +109,7 @@ function returns a pointer to the duplicated
 string.
 It returns NULL if insufficient memory was available, with
 .I errno
-set to indicate the cause of the error.
+set to indicate the error.
 .SH ERRORS
 .TP
 .B ENOMEM

man3/sysconf.3

@@ -330,7 +330,7 @@ is one of the following:
 .IP * 3
 On error, \-1 is returned and
 .I errno
-is set to indicate the cause of the error
+is set to indicate the error
 (for example,
 .BR EINVAL ,
 indicating that

man3/tempnam.3

@@ -102,7 +102,7 @@ On success, the
 function returns a pointer to a unique temporary filename.
 It returns NULL if a unique name cannot be generated, with
 .I errno
-set to indicate the cause of the error.
+set to indicate the error.
 .SH ERRORS
 .TP
 .B ENOMEM

man3/timegm.3

@@ -71,7 +71,7 @@ On error, they return the value
 .I (time_t)\ \-1
 and set
 .I errno
-to indicate the cause of the error.
+to indicate the error.
 .SH ERRORS
 .TP
 .B EOVERFLOW

man3/uselocale.3

@@ -81,7 +81,7 @@ On error, it returns
 .IR "(locale_t)\ 0" ,
 and sets
 .I errno
-to indicate the cause of the error.
+to indicate the error.
 .SH ERRORS
 .TP
 .B EINVAL

man3/usleep.3

@@ -69,7 +69,7 @@ The
 function returns 0 on success.
 On error, \-1 is returned, with
 .I errno
-set to indicate the cause of the error.
+set to indicate the error.
 .SH ERRORS
 .TP
 .B EINTR

man3/wcsdup.3

@@ -56,7 +56,7 @@ On success,
 returns a pointer to the new wide-character string.
 On error, it returns NULL, with
 .I errno
-set to indicate the cause of the error.
+set to indicate the error.
 .SH ERRORS
 .TP
 .B ENOMEM