commit dbbba9dd08c6225b8c443eb9e03eda3a40334781
parent 91dfc7988d2b3f452e2e852861f388eb665aeb28
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date: Fri, 8 Jul 2022 06:18:01 +0200
New blog post
Diffstat:
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
@@ -0,0 +1,125 @@
+# The man page reading club: shutdown(8)
+
+I would like to write about more interesting things, but I do not have
+time or energy to do so. I need to shut down for a little while.
+
+## Sleeping in a sleepless time
+
+*Reading. Learning. Fun. Tired.*
+
+```
+$ date
+Thu Jul 7 22:57:50 CEST 2022
+```
+
+*Not too late. You should do something.*
+
+```
+$ man man
+NAME
+ man - display manual pages
+```
+
+*No, you have already done that one. What should you do?*
+
+```
+$ date
+Thu Jul 7 22:59:48 CEST 2022
+```
+
+*This is not going anywhere. Is it time to go to sleep? Who knows,
+during the covid lockdown - ahem, nuclear winter - every hour looks the same.
+Maybe it is time to go to sleep. To shutdown.*
+
+## shutdown(8)
+
+*Follow along at [man.openbsd.org](https://man.openbsd.org/OpenBSD-7.1/shutdown)*
+
+```
+SYNOPSIS
+ shutdown [-] [-dfhknpr] time [warning-message ...]
+
+DESCRIPTION
+ shutdown provides an automated shutdown procedure for superusers to
+ nicely notify users when the system is shutting down, saving them from
+ system administrators, hackers, and gurus, who would otherwise not bother
+ with such niceties. When the shutdown command is issued without options,
+ the system is placed in single user mode at the indicated time after
+ shutting down all system services.
+```
+
+As it sometimes happens, the first few lines of the manual page hint to some
+arcane background that you cannot quite grasp. However, the bottom line is
+clear: `shutdwon` shuts the system down.
+
+```
+The options are as follows:
+ -d When used with -h, -p, or -r causes system to perform a dump.
+ This option is useful for debugging system dump procedures [...].
+```
+
+Good to keep in mind. But this time we are not in for an in-depth analysis of
+a classic UNIX command. We just want to shut down. Let's skip a few of the
+other options.
+
+```
+ -p The system is powered down at the specified time. The -p flag is
+ passed on to halt(8), causing machines which support automatic
+ power down to do so after halting.
+
+ -r shutdown execs reboot(8) at the specified time.
+```
+
+Yes, these sound like things I would like to do. How do I tell it to
+shut down now?
+
+```
+ time time is the time at which shutdown will bring the system down and
+ may be the word now (indicating an immediate shutdown) or specify
+ a future time in one of two formats: +number or yymmddhhmm,
+ where the year, month, and day may be defaulted to the current
+ system values. The first form brings the system down in number
+ minutes and the second at the absolute time specified.
+```
+
+Great!
+
+```
+ warning-message
+ Any other arguments comprise the warning message that is
+ broadcast to users currently logged into the system.
+ - If `-' is supplied as an option, the warning message is read from
+ the standard input.
+```
+
+Who do we have to warn about the shutdown? We are the only user anyway, right?
+
+```
+# echo 'the hours rise up putting off stars and it is
+> dawn' | shutdown -p now -
+```
+
+## Conclusions
+
+At the moment of writing this blog post, I am tired. I had a busy week.
+I wanted to write an interesting blog post about something like
+sh(1), but I could not find the time. However, shutting down my pc earlier
+today inspired me to write this short blog entry.
+
+`shutdown` is an interesting command. It seems like it should be
+straightforward: "computer, please shut down". But the syntax for this
+simple instruction is quite complicated, and it offers us many more option
+than we would ever want to use, at least in the 21st century. Moreover, as
+indicated by the `#` instead of the `$` in the last command, one needs
+superuser privileges to shut down a classic UNIX system.
+
+This is because, in the time of mainframes, *shutting down* was not such a
+simple operation: multiple users might have been connected to the main
+computer, and shutting the whole system down without at least telling them
+was rude. At least this is my guess, I was not there at the time.
+
+It would certainly be interesting to dig into the history of computer systems,
+mainframes and how administrators used to shut them down when multiple users
+where logged in. But I am not going to do it now.
+
+Good night.
diff --git a/src/blog/blog.md b/src/blog/blog.md
@@ -2,6 +2,7 @@
[RSS Feed](feed.xml)
+* 2022-07-07 [The man page reading club: shutdown(8)](2022-07-07-shutdown)
* 2022-06-12 [The UNIX shell as an IDE: look stuff up with sed](2022-06-12-shell-ide-sed)
* 2022-06-08 [The man page reading club: more(1)](2022-06-08-more)
* 2022-06-04 [The gemini protocol](2022-06-04-gemini)
diff --git a/src/blog/feed.xml b/src/blog/feed.xml
@@ -9,6 +9,13 @@ Thoughts about software, computers and whatever I feel like sharing
</description>
<item>
+<title>The man page reading club: shutdown(8)</title>
+<link>https://sebastiano.tronto.net/blog/2022-07-07-shutdown</link>
+<description>The man page reading club: shutdown(8)</description>
+<pubDate>2022-07-07</pubDate>
+</item>
+
+<item>
<title>The UNIX shell as an IDE: look stuff up with sed</title>
<link>https://sebastiano.tronto.net/blog/2022-06-12-shell-ide-sed</link>
<description>The UNIX shell as an IDE: look stuff up with sed</description>
