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authorSebastiano Tronto <sebastiano@tronto.net>2022-07-08 06:18:01 +0200
committerSebastiano Tronto <sebastiano@tronto.net>2022-07-08 06:18:01 +0200
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parent91dfc7988d2b3f452e2e852861f388eb665aeb28 (diff)
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New blog post
-rw-r--r--src/blog/2022-07-07-shutdown/shutdown.md125
-rw-r--r--src/blog/blog.md1
-rw-r--r--src/blog/feed.xml7
3 files changed, 133 insertions, 0 deletions
diff --git a/src/blog/2022-07-07-shutdown/shutdown.md b/src/blog/2022-07-07-shutdown/shutdown.md
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1# The man page reading club: shutdown(8)
2
3I would like to write about more interesting things, but I do not have
4time or energy to do so. I need to shut down for a little while.
5
6## Sleeping in a sleepless time
7
8*Reading. Learning. Fun. Tired.*
9
10```
11$ date
12Thu Jul 7 22:57:50 CEST 2022
13```
14
15*Not too late. You should do something.*
16
17```
18$ man man
19NAME
20 man - display manual pages
21```
22
23*No, you have already done that one. What should you do?*
24
25```
26$ date
27Thu Jul 7 22:59:48 CEST 2022
28```
29
30*This is not going anywhere. Is it time to go to sleep? Who knows,
31during the covid lockdown - ahem, nuclear winter - every hour looks the same.
32Maybe it is time to go to sleep. To shutdown.*
33
34## shutdown(8)
35
36*Follow along at [man.openbsd.org](https://man.openbsd.org/OpenBSD-7.1/shutdown)*
37
38```
39SYNOPSIS
40 shutdown [-] [-dfhknpr] time [warning-message ...]
41
42DESCRIPTION
43 shutdown provides an automated shutdown procedure for superusers to
44 nicely notify users when the system is shutting down, saving them from
45 system administrators, hackers, and gurus, who would otherwise not bother
46 with such niceties. When the shutdown command is issued without options,
47 the system is placed in single user mode at the indicated time after
48 shutting down all system services.
49```
50
51As it sometimes happens, the first few lines of the manual page hint to some
52arcane background that you cannot quite grasp. However, the bottom line is
53clear: `shutdwon` shuts the system down.
54
55```
56The options are as follows:
57 -d When used with -h, -p, or -r causes system to perform a dump.
58 This option is useful for debugging system dump procedures [...].
59```
60
61Good to keep in mind. But this time we are not in for an in-depth analysis of
62a classic UNIX command. We just want to shut down. Let's skip a few of the
63other options.
64
65```
66 -p The system is powered down at the specified time. The -p flag is
67 passed on to halt(8), causing machines which support automatic
68 power down to do so after halting.
69
70 -r shutdown execs reboot(8) at the specified time.
71```
72
73Yes, these sound like things I would like to do. How do I tell it to
74shut down now?
75
76```
77 time time is the time at which shutdown will bring the system down and
78 may be the word now (indicating an immediate shutdown) or specify
79 a future time in one of two formats: +number or yymmddhhmm,
80 where the year, month, and day may be defaulted to the current
81 system values. The first form brings the system down in number
82 minutes and the second at the absolute time specified.
83```
84
85Great!
86
87```
88 warning-message
89 Any other arguments comprise the warning message that is
90 broadcast to users currently logged into the system.
91 - If `-' is supplied as an option, the warning message is read from
92 the standard input.
93```
94
95Who do we have to warn about the shutdown? We are the only user anyway, right?
96
97```
98# echo 'the hours rise up putting off stars and it is
99> dawn' | shutdown -p now -
100```
101
102## Conclusions
103
104At the moment of writing this blog post, I am tired. I had a busy week.
105I wanted to write an interesting blog post about something like
106sh(1), but I could not find the time. However, shutting down my pc earlier
107today inspired me to write this short blog entry.
108
109`shutdown` is an interesting command. It seems like it should be
110straightforward: "computer, please shut down". But the syntax for this
111simple instruction is quite complicated, and it offers us many more option
112than we would ever want to use, at least in the 21st century. Moreover, as
113indicated by the `#` instead of the `$` in the last command, one needs
114superuser privileges to shut down a classic UNIX system.
115
116This is because, in the time of mainframes, *shutting down* was not such a
117simple operation: multiple users might have been connected to the main
118computer, and shutting the whole system down without at least telling them
119was rude. At least this is my guess, I was not there at the time.
120
121It would certainly be interesting to dig into the history of computer systems,
122mainframes and how administrators used to shut them down when multiple users
123where logged in. But I am not going to do it now.
124
125Good night.
diff --git a/src/blog/blog.md b/src/blog/blog.md
index 5b777ad..7b8095b 100644
--- a/src/blog/blog.md
+++ b/src/blog/blog.md
@@ -2,6 +2,7 @@
2 2
3[RSS Feed](feed.xml) 3[RSS Feed](feed.xml)
4 4
5* 2022-07-07 [The man page reading club: shutdown(8)](2022-07-07-shutdown)
5* 2022-06-12 [The UNIX shell as an IDE: look stuff up with sed](2022-06-12-shell-ide-sed) 6* 2022-06-12 [The UNIX shell as an IDE: look stuff up with sed](2022-06-12-shell-ide-sed)
6* 2022-06-08 [The man page reading club: more(1)](2022-06-08-more) 7* 2022-06-08 [The man page reading club: more(1)](2022-06-08-more)
7* 2022-06-04 [The gemini protocol](2022-06-04-gemini) 8* 2022-06-04 [The gemini protocol](2022-06-04-gemini)
diff --git a/src/blog/feed.xml b/src/blog/feed.xml
index 567c6b2..a91f184 100644
--- a/src/blog/feed.xml
+++ b/src/blog/feed.xml
@@ -9,6 +9,13 @@ Thoughts about software, computers and whatever I feel like sharing
9</description> 9</description>
10 10
11<item> 11<item>
12<title>The man page reading club: shutdown(8)</title>
13<link>https://sebastiano.tronto.net/blog/2022-07-07-shutdown</link>
14<description>The man page reading club: shutdown(8)</description>
15<pubDate>2022-07-07</pubDate>
16</item>
17
18<item>
12<title>The UNIX shell as an IDE: look stuff up with sed</title> 19<title>The UNIX shell as an IDE: look stuff up with sed</title>
13<link>https://sebastiano.tronto.net/blog/2022-06-12-shell-ide-sed</link> 20<link>https://sebastiano.tronto.net/blog/2022-06-12-shell-ide-sed</link>
14<description>The UNIX shell as an IDE: look stuff up with sed</description> 21<description>The UNIX shell as an IDE: look stuff up with sed</description>

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