[PATCH 00/17] Patches from others

[PATCH 00/17] Patches from others

[Alejandro Colomar]

Hello Michael,

These are the patches that I have merged from others.

Cheers,

Alex

---

Akihiro Motoki (4):
  move_pages.2: ffix
  semctl.2: ffix
  fanotify.7: ffix
  signalfd.2: tfix

Alejandro Colomar (3):
  setbuf.3: tfix
  sigwaitinfo.2: tfix
  getopt.3: Minor tweaks to James' patch

Aurelien Aptel (1):
  flock.2: add CIFS details

Borislav Petkov (1):
  sigaltstack.2: tfix

Dmitry V. Levin (2):
  move_pages.2: ffix
  ptrace.2: mention PTRACE_GET_SYSCALL_INFO in RETURN VALUE section

Jakub Wilk (2):
  Changes.old: tfix
  exit_group.2, getunwind.2: tfix

James O. D. Hunt (1):
  getopt.3: Clarify behaviour

Johannes Berg (1):
  clone.2: tfix

Vishwajith K (1):
  shmop.2: tfix

Štěpán Němec (1):
  execve.2: tfix

 Changes.old        |  6 +++---
 man2/clone.2       |  2 +-
 man2/execve.2      |  2 +-
 man2/exit_group.2  |  2 +-
 man2/flock.2       | 25 +++++++++++++++++++++++++
 man2/getunwind.2   |  2 +-
 man2/move_pages.2  |  3 ++-
 man2/ptrace.2      |  7 +++++--
 man2/semctl.2      |  2 +-
 man2/shmop.2       |  4 ++--
 man2/sigaltstack.2 |  2 +-
 man2/signalfd.2    |  2 +-
 man2/sigwaitinfo.2 |  2 +-
 man3/getopt.3      | 23 +++++++++++++++++++++++
 man3/setbuf.3      |  2 +-
 man7/fanotify.7    |  2 +-
 16 files changed, 70 insertions(+), 18 deletions(-)

-- 
2.31.1

[PATCH 01/17] flock.2: add CIFS details

[Alejandro Colomar]

From: Aurelien Aptel <aaptel@suse.com>

CIFS flock() locks behave differently than the standard. Give overview
of those differences.

Here is the rendered text:

CIFS details
  In Linux kernels up to 5.4, flock() is not propagated over SMB.  A file
  with such locks will not appear locked for remote clients.

  Since Linux 5.5, flock() locks are emulated with SMB  byte-range  locks
  on  the  entire  file.   Similarly to NFS, this means that fcntl(2) and
  flock() locks interact with one another.  Another important side-effect
  is  that  the  locks  are not advisory anymore: any IO on a locked file
  will always fail with EACCES when done from a separate file descriptor.
  This  difference  originates from the design of locks in the SMB proto-
  col, which provides mandatory locking semantics.

  Remote and mandatory locking semantics  may  vary  with  SMB  protocol,
  mount options and server type.  See mount.cifs(8) for additional infor-
  mation.

Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Discussion: linux-man <https://lore.kernel.org/linux-man/20210302154831.17000-1-aaptel@suse.com/>
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
---
 man2/flock.2 | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/man2/flock.2 b/man2/flock.2
index 328377365..61822c9bc 100644
--- a/man2/flock.2
+++ b/man2/flock.2
@@ -239,6 +239,31 @@ see the discussion of the
 .I "local_lock"
 option in
 .BR nfs (5).
+.SS CIFS details
+In Linux kernels up to 5.4,
+.BR flock ()
+is not propagated over SMB.
+A file with such locks will not appear locked for remote clients.
+.PP
+Since Linux 5.5,
+.BR flock ()
+locks are emulated with SMB byte-range locks on the entire file.
+Similarly to NFS, this means that
+.BR fcntl (2)
+and
+.BR flock ()
+locks interact with one another.
+Another important side-effect is that the locks are not advisory anymore:
+any IO on a locked file will always fail with
+.BR EACCES
+when done from a separate file descriptor.
+This difference originates from the design of locks in the SMB protocol,
+which provides mandatory locking semantics.
+.PP
+Remote and mandatory locking semantics may vary with SMB protocol, mount options and server type.
+See
+.BR mount.cifs (8)
+for additional information.
 .SH SEE ALSO
 .BR flock (1),
 .BR close (2),
-- 
2.31.1

[PATCH 02/17] sigaltstack.2: tfix

[Alejandro Colomar]

From: Borislav Petkov <bp@suse.de>

Add a missing "to" in an "in order to" formulation.

Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
---
 man2/sigaltstack.2 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/man2/sigaltstack.2 b/man2/sigaltstack.2
index c8d5c184f..53268ccbe 100644
--- a/man2/sigaltstack.2
+++ b/man2/sigaltstack.2
@@ -111,7 +111,7 @@ Clear the alternate signal stack settings on entry to the signal handler.
 When the signal handler returns,
 the previous alternate signal stack settings are restored.
 .IP
-This flag was added in order make it safe
+This flag was added in order to make it safe
 to switch away from the signal handler with
 .BR swapcontext (3).
 Without this flag, a subsequently handled signal will corrupt
-- 
2.31.1

[PATCH 03/17] setbuf.3: tfix

[Alejandro Colomar]

Reported-by: Zhiheng Li <phoenix_lzh@sina.com>
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
---
 man3/setbuf.3 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/man3/setbuf.3 b/man3/setbuf.3
index 5e5d57f89..0d7cca8f9 100644
--- a/man3/setbuf.3
+++ b/man3/setbuf.3
@@ -229,7 +229,7 @@ int
 main(void)
 {
     char buf[BUFSIZ];
-    setbuf(stdin, buf);
+    setbuf(stdout, buf);
     printf("Hello, world!\en");
     return 0;
 }
-- 
2.31.1

[PATCH 04/17] clone.2: tfix

[Alejandro Colomar]

From: Johannes Berg <johannes@sipsolutions.net>

Despite my mention of this spawning a hilarious discussion
on IRC, this alignment restriction should be 128-bit, not
126-bit.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
---
 man2/clone.2 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/man2/clone.2 b/man2/clone.2
index 818e584ce..838fbd669 100644
--- a/man2/clone.2
+++ b/man2/clone.2
@@ -1418,7 +1418,7 @@ was an invalid.
 .TP
 .BR EINVAL " (AArch64 only, Linux 4.6 and earlier)"
 .I stack
-was not aligned to a 126-bit boundary.
+was not aligned to a 128-bit boundary.
 .TP
 .B ENOMEM
 Cannot allocate sufficient memory to allocate a task structure for the
-- 
2.31.1

[PATCH 05/17] move_pages.2: ffix

[Alejandro Colomar]

From: "Dmitry V. Levin" <ldv@altlinux.org>

Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
---
 man2/move_pages.2 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/man2/move_pages.2 b/man2/move_pages.2
index 279de7568..69c182f95 100644
--- a/man2/move_pages.2
+++ b/man2/move_pages.2
@@ -24,7 +24,7 @@ move_pages \- move individual pages of a process to another node
 .nf
 .B #include <numaif.h>
 .PP
-.BI "long move_pages(int " pid ", unsigned long count, void **" pages ,
+.BI "long move_pages(int " pid ", unsigned long " count ", void **" pages ,
 .BI "                const int *" nodes ", int *" status ", int " flags );
 .fi
 .PP
-- 
2.31.1

[PATCH 06/17] ptrace.2: mention PTRACE_GET_SYSCALL_INFO in RETURN VALUE section

[Alejandro Colomar]

From: "Dmitry V. Levin" <ldv@altlinux.org>

Mirror the wording about PTRACE_GET_SYSCALL_INFO return value semantics
from "DESCRIPTION" section to "RETURN VALUE" section.

Reported-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Complements: fc91449cb "ptrace.2: Document PTRACE_GET_SYSCALL_INFO"
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
---
 man2/ptrace.2 | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/man2/ptrace.2 b/man2/ptrace.2
index 56dcbbf4b..ffaf8db0d 100644
--- a/man2/ptrace.2
+++ b/man2/ptrace.2
@@ -2327,8 +2327,11 @@ On success, the
 requests return the requested data (but see NOTES),
 the
 .B PTRACE_SECCOMP_GET_FILTER
-request returns the number of instructions in the BPF program, and
-other requests return zero.
+request returns the number of instructions in the BPF program,
+the
+.B PTRACE_GET_SYSCALL_INFO
+request returns the number of bytes available to be written by the kernel,
+and other requests return zero.
 .PP
 On error, all requests return \-1, and
 .I errno
-- 
2.31.1

[PATCH 07/17] Changes.old: tfix

[Alejandro Colomar]

From: Jakub Wilk <jwilk@jwilk.net>

Signed-off-by: Jakub Wilk <jwilk@jwilk.net>
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
---
 Changes.old | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Changes.old b/Changes.old
index f863583b1..067fce382 100644
--- a/Changes.old
+++ b/Changes.old
@@ -53581,7 +53581,7 @@ Various pages
             Generally, place '||' at start of a line, rather than the end of
             the previous line.
 
-            Rationale: this placement clearly indicates that that each piece
+            Rationale: this placement clearly indicates that each piece
             is an alternative.
 
 Various pages
@@ -54119,7 +54119,7 @@ system.3
 environ.7
     Bastien Roucariès
         Reorder the text
-            Move the the text describing how to set environment variable before
+            Move the text describing how to set environment variable before
             the list(s) of variables in order to improve readability.
     Bastien Roucariès
         Document convention of string in environ
@@ -54152,7 +54152,7 @@ man-pages.7
     Michael Kerrisk
         Add a FORMATTING AND WORDING CONVENTIONS section
             In man-pages-5.11, a large number of pages were edited to achieve
-            greater consistency in the SYNOPIS, RETURN VALUE and ATTRIBUTES
+            greater consistency in the SYNOPSIS, RETURN VALUE and ATTRIBUTES
             sections. To avoid future inconsistencies, try to capture some of
             the preferred conventions in text in man-pages(7).
     Michael Kerrisk
-- 
2.31.1

[PATCH 08/17] exit_group.2, getunwind.2: tfix

[Alejandro Colomar]

From: Jakub Wilk <jwilk@jwilk.net>

Signed-off-by: Jakub Wilk <jwilk@jwilk.net>
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
---
 man2/exit_group.2 | 2 +-
 man2/getunwind.2  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/man2/exit_group.2 b/man2/exit_group.2
index b512927d4..d197f1f2e 100644
--- a/man2/exit_group.2
+++ b/man2/exit_group.2
@@ -28,7 +28,7 @@ exit_group \- exit all threads in a process
 .SH SYNOPSIS
 .nf
 .BR "#include <sys/syscall.h>" "       /* Definition of " SYS_* " constants */"
-.B #inlcude <unistd.h>
+.B #include <unistd.h>
 .PP
 .BI "noreturn void syscall(SYS_exit_group, int " status );
 .fi
diff --git a/man2/getunwind.2 b/man2/getunwind.2
index 2c44506c7..403bd7770 100644
--- a/man2/getunwind.2
+++ b/man2/getunwind.2
@@ -31,7 +31,7 @@ getunwind \- copy the unwind data to caller's buffer
 .nf
 .B #include <linux/unwind.h>
 .BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
-.B #inlcude <unistd.h>
+.B #include <unistd.h>
 .PP
 .BI "long syscall(SYS_getunwind, void " *buf ", size_t " buf_size );
 .fi
-- 
2.31.1

[PATCH 09/17] sigwaitinfo.2: tfix

[Alejandro Colomar]

Fix wording issue introduced in commit
bf1298c9e5053f55dea43e74255dae5ec57f251e.

Reported-by: Chris Keilbart <keilbartchris@gmail.com>
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
---
 man2/sigwaitinfo.2 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/man2/sigwaitinfo.2 b/man2/sigwaitinfo.2
index 5cd88c557..00bc50485 100644
--- a/man2/sigwaitinfo.2
+++ b/man2/sigwaitinfo.2
@@ -120,7 +120,7 @@ set to indicate the error.
 .B EAGAIN
 No signal in
 .I set
-was became pending within the
+became pending within the
 .I timeout
 period specified to
 .BR sigtimedwait ().
-- 
2.31.1

[PATCH 10/17] getopt.3: Clarify behaviour

[Alejandro Colomar]

From: "James O. D. Hunt" <jamesodhunt@gmail.com>

Improved the `getopt(3)` man page in the following ways:

1) Defined the existing term "legitimate option character".
2) Added an additional NOTE stressing that arguments are parsed in strict
   order and the implications of this when numeric options are utilised.

Signed-off-by: James O. D. Hunt <jamesodhunt@gmail.com>
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
---
 man3/getopt.3 | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/man3/getopt.3 b/man3/getopt.3
index 921e747f8..e88321ed0 100644
--- a/man3/getopt.3
+++ b/man3/getopt.3
@@ -126,6 +126,11 @@ Then \fIoptind\fP is the index in \fIargv\fP of the first
 .PP
 .I optstring
 is a string containing the legitimate option characters.
+A legitimate option character is any visible one byte
+.BR ascii (7)
+character (for which
+.BR isgraph (3)
+would return nonzero) that is not dash (\(aq\-\(aq) or colon (\(aq:\(aq).
 If such a
 character is followed by a colon, the option requires an argument, so
 .BR getopt ()
@@ -402,6 +407,24 @@ routine that rechecks
 .B POSIXLY_CORRECT
 and checks for GNU extensions in
 .IR optstring .)
+.PP
+Command-line arguments are parsed in strict order
+meaning that an option requiring an argument will consume the next argument,
+regardless of whether that argument is the correctly specified option argument
+or simply the next option
+(in the scenario the user mis-specifies the command line).
+For example, if
+.I optstring
+is specified as "1n:"
+and the user specifies the command line arguments incorrectly as
+.IR "prog\ \-n\ \-1" ,
+the
+.I \-n
+option will be given the
+.B optarg
+value "\-1", and the
+.I \-1
+option will be considered to have not been specified.
 .SH EXAMPLES
 .SS getopt()
 The following trivial example program uses
-- 
2.31.1

[PATCH 11/17] getopt.3: Minor tweaks to James' patch

[Alejandro Colomar]

The rest of the page writes the characters without naming them.
Follow that convention.

Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
---
 man3/getopt.3 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/man3/getopt.3 b/man3/getopt.3
index e88321ed0..0d6ad1c54 100644
--- a/man3/getopt.3
+++ b/man3/getopt.3
@@ -130,7 +130,7 @@ A legitimate option character is any visible one byte
 .BR ascii (7)
 character (for which
 .BR isgraph (3)
-would return nonzero) that is not dash (\(aq\-\(aq) or colon (\(aq:\(aq).
+would return nonzero) that is not \(aq\-\(aq or \(aq:\(aq.
 If such a
 character is followed by a colon, the option requires an argument, so
 .BR getopt ()
-- 
2.31.1

[PATCH 12/17] shmop.2: tfix

[Alejandro Colomar]

From: Vishwajith K <vishuvikas1996@gmail.com>

Signed-off-by: Vishwajith K <vishuvikas1996@gmail.com>
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
---
 man2/shmop.2 | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/man2/shmop.2 b/man2/shmop.2
index 3a6c908ee..c7e66af0e 100644
--- a/man2/shmop.2
+++ b/man2/shmop.2
@@ -387,8 +387,8 @@ main(int argc, char *argv[])
         errExit("shmget");
 
     semid = semget(IPC_PRIVATE, 1, IPC_CREAT | 0600);
-    if (shmid == \-1)
-        errExit("shmget");
+    if (semid == \-1)
+        errExit("semget");
 
     /* Attach shared memory into our address space. */
 
-- 
2.31.1

[PATCH 13/17] execve.2: tfix

[Alejandro Colomar]

From: Štěpán Němec <stepnem@gmail.com>

Signed-off-by: Štěpán Němec <stepnem@gmail.com>
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
---
 man2/execve.2 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/man2/execve.2 b/man2/execve.2
index 1609bce04..c18ca5412 100644
--- a/man2/execve.2
+++ b/man2/execve.2
@@ -141,7 +141,7 @@ similarly, the effective group ID is copied to the saved set-group-ID.
 This copying takes place after any effective ID changes that occur
 because of the set-user-ID and set-group-ID mode bits.
 .PP
-The process's real UID and real GID, as well its supplementary group IDs,
+The process's real UID and real GID, as well as its supplementary group IDs,
 are unchanged by a call to
 .BR execve ().
 .PP
-- 
2.31.1

[PATCH 14/17] move_pages.2: ffix

[Alejandro Colomar]

From: Akihiro Motoki <amotoki@gmail.com>

Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
---
 man2/move_pages.2 | 1 +
 1 file changed, 1 insertion(+)

diff --git a/man2/move_pages.2 b/man2/move_pages.2
index 69c182f95..f229df177 100644
--- a/man2/move_pages.2
+++ b/man2/move_pages.2
@@ -180,6 +180,7 @@ The number of nonmigrated pages if they were the result of nonfatal
 reasons (since
 .\" commit a49bd4d7163707de377aee062f17befef6da891b
 Linux 4.17).
+.TP
 .B E2BIG
 Too many pages to move.
 Since Linux 2.6.29,
-- 
2.31.1

[PATCH 15/17] semctl.2: ffix

[Alejandro Colomar]

From: Akihiro Motoki <amotoki@gmail.com>

Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
---
 man2/semctl.2 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/man2/semctl.2 b/man2/semctl.2
index ac8bd906d..23729bf79 100644
--- a/man2/semctl.2
+++ b/man2/semctl.2
@@ -377,7 +377,7 @@ the semaphore set.
 .TP
 .B SETVAL
 Set the semaphore value
-.BR ( semval )
+.RB ( semval )
 to
 .I arg.val
 for the
-- 
2.31.1

[PATCH 16/17] fanotify.7: ffix

[Alejandro Colomar]

From: Akihiro Motoki <amotoki@gmail.com>

Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
---
 man7/fanotify.7 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/man7/fanotify.7 b/man7/fanotify.7
index ebe5c1d7f..6a7e70d75 100644
--- a/man7/fanotify.7
+++ b/man7/fanotify.7
@@ -147,7 +147,7 @@ influences what data structures are returned to the event listener for each
 event.
 Events reported to a group initialized with one of these flags will
 use file handles to identify filesystem objects instead of file descriptors.
-.TP
+.PP
 After a successful
 .BR read (2),
 the read buffer contains one or more of the following structures:
-- 
2.31.1

[PATCH 17/17] signalfd.2: tfix

[Alejandro Colomar]

From: Akihiro Motoki <amotoki@gmail.com>

Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
---
 man2/signalfd.2 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/man2/signalfd.2 b/man2/signalfd.2
index e362d1f72..102679c0d 100644
--- a/man2/signalfd.2
+++ b/man2/signalfd.2
@@ -196,7 +196,7 @@ struct signalfd_siginfo {
     uint64_t ssi_addr;     /* Address that generated signal
                               (for hardware\-generated signals) */
     uint16_t ssi_addr_lsb; /* Least significant bit of address
-                              (SIGBUS; since Linux 2.6.37)
+                              (SIGBUS; since Linux 2.6.37) */
 .\" ssi_addr_lsb: commit b8aeec34175fc8fe8b0d40efea4846dfc1ba663e
     uint8_t  pad[\fIX\fP];       /* Pad size to 128 bytes (allow for
                               additional fields in the future) */
-- 
2.31.1

Re: [PATCH 00/17] Patches from others

[Michael Kerrisk (man-pages)]

Hello Alex,

On 5/10/21 8:19 AM, Alejandro Colomar wrote:
> 
> Hello Michael,
> 
> These are the patches that I have merged from others.
> 
> Cheers,
> 
> Alex

These all look good, and I've applied them all.
Thank you for accumulating these in my absence!

Cheers,

Michael

> ---
> 
> Akihiro Motoki (4):
>   move_pages.2: ffix
>   semctl.2: ffix
>   fanotify.7: ffix
>   signalfd.2: tfix
> 
> Alejandro Colomar (3):
>   setbuf.3: tfix
>   sigwaitinfo.2: tfix
>   getopt.3: Minor tweaks to James' patch
> 
> Aurelien Aptel (1):
>   flock.2: add CIFS details
> 
> Borislav Petkov (1):
>   sigaltstack.2: tfix
> 
> Dmitry V. Levin (2):
>   move_pages.2: ffix
>   ptrace.2: mention PTRACE_GET_SYSCALL_INFO in RETURN VALUE section
> 
> Jakub Wilk (2):
>   Changes.old: tfix
>   exit_group.2, getunwind.2: tfix
> 
> James O. D. Hunt (1):
>   getopt.3: Clarify behaviour
> 
> Johannes Berg (1):
>   clone.2: tfix
> 
> Vishwajith K (1):
>   shmop.2: tfix
> 
> Štěpán Němec (1):
>   execve.2: tfix
> 
>  Changes.old        |  6 +++---
>  man2/clone.2       |  2 +-
>  man2/execve.2      |  2 +-
>  man2/exit_group.2  |  2 +-
>  man2/flock.2       | 25 +++++++++++++++++++++++++
>  man2/getunwind.2   |  2 +-
>  man2/move_pages.2  |  3 ++-
>  man2/ptrace.2      |  7 +++++--
>  man2/semctl.2      |  2 +-
>  man2/shmop.2       |  4 ++--
>  man2/sigaltstack.2 |  2 +-
>  man2/signalfd.2    |  2 +-
>  man2/sigwaitinfo.2 |  2 +-
>  man3/getopt.3      | 23 +++++++++++++++++++++++
>  man3/setbuf.3      |  2 +-
>  man7/fanotify.7    |  2 +-
>  16 files changed, 70 insertions(+), 18 deletions(-)
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/