commit 98934e523c9d05823d7358018017fd880def9716
parent 6bab41791269c72c7913417e735d06e3e6bf6b56
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date: Wed, 8 Jun 2022 15:32:37 +0200
Added blog post. Fixed padding for code in pre.
Diffstat:
6 files changed, 310 insertions(+), 106 deletions(-)
diff --git a/src/blog/2022-06-08-more/more.md b/src/blog/2022-06-08-more/more.md
@@ -0,0 +1,192 @@
+# The man page reading club: more(1)
+
+In the second episode of this blog series we are going to cover a UNIX
+pager. Instead of the popular less(1), we are going to check out the
+classic more(1).
+
+## In the bunker
+
+*After installing your new OS and checking out the basic documentation,
+you are excited to discover what your laptop can do. But there is
+something keeping you back. Maybe it's the rumors that the nuclear
+winter will be raging for years to come and you are in there for the
+long run. No, it's not that.*
+
+*You feel that learning is fun, and fun is precious, so you should not
+waste it. Entertainment is a scarce resource in the bunker: social
+interactions are awkward, and the battery-charging gym only offers
+re-runs of crappy mainstream reality shows.*
+
+*You dedice to play the slow game and
+[RTFM](https://en.wikipedia.org/wiki/RTFM) some more before doing actual
+work. You have just found out that the man(1) program calls an external
+utility, called less(1), to actually display the page. Learning more
+abut this makes sense.*
+
+```
+$ man less
+```
+
+*You start reading, but you soon feel overwhelmed: this manual page is a
+fucking novel! There are pages and pages of options, and on top of that
+there are commands, and you can't make sense of what is actually useful.
+You scroll back to the top of the page and something catches your eyes:*
+
+```
+less is similar to the traditional more(1), but with many more features.
+```
+
+*Hoping it will be easier to grasp, you decide to look into more(1)*
+
+```
+$ man more
+```
+
+*No, wait! Let's use what we learned [last time](../2022-05-29-man):*
+
+```
+$ PAGER=more man more
+```
+
+## more(1)
+
+*Follow along at [man.openbsd.org](https://man.openbsd.org/OpenBSD-7.1/more)*
+
+The description of more(1) starts with
+
+```
+The more pager displays text one screenful at a time. After showing each
+screenful, it prompts the user for a command. Most commands scroll the text
+or move to a different place in the file, while some switch to another file.
+```
+
+So "commands" seem to be the interesting part. There are also a handful of
+options, but they seem quite technical and not so interesting. Just to name
+a few: `-n` changes the number of lines per screenful, `-p` can be used to
+execute a command when a file is first opened and `-t` can be used to view
+a file containing a specific "tag". This last one is enticing, but it
+redirects to ctags(1), which may be a good topic for a future post.
+
+Let's move on to the juicy part!
+
+```
+COMMANDS
+ Interactive commands for more are based on vi(1). Some commands may be
+ preceded by a decimal number, called N in the descriptions below. In the
+ following descriptions, ^X means control-X.
+```
+
+The first command is `h`, which displays a help page for more(1). It is
+basically a more terse, cheatsheet-like version of the COMMANDS section
+that we are reading.
+
+The basic navigation commands scroll the current page up or down. They can
+all be preceded by the number of lines to be scrolled, but have different
+defaults: `j` (or `RETURN`) scrolls down one line, `k` up one line. `f`
+(or `SPACE`, or `^F`) and `b` (or `^B`) scroll one window down and up,
+respectively. `d` and `u` (or `^D` and `^U`) scroll half a
+window down and up, respectively. It is not documented in the manual, but
+arrow keys, and `PgUp` and `PgDn`, seem to work just fine too.
+
+Perhaps more interestingly, the commands `m` and `'` (single quote) allow
+you to "mark" certain lines and move to them:
+
+```
+m Followed by any lowercase letter, marks the current position with that letter.
+
+' (Single quote.) Followed by any lowercase letter, returns to the position
+ which was previously marked with that letter. Followed by another single
+ quote, returns to the position at whcih the last "large" movement command was
+ executed, or the beginning of the file if no such movements have occurred.
+ All marks are lost when a new file is examined.
+```
+
+There is also a search function:
+
+```
+/pattern Search forward in the file for the N-th line containing the pattern.
+ N defaults to 1. The pattern is a basic regular expression (BRE).
+ See re_format(7) for more information on regular expressions.
+ The search starts at the second line displayed.
+```
+
+Regular expressions are a powerful tool, but we will not see them in detail
+today. For now it is enough to know that plain text is a perfectly fine
+regular expression.
+
+There are alternative commands for searching: using `?` instead of `/`
+searches backwards from the top line, while `/!` and `?!` search for lines
+that *do not* match the pattern. In each case the search command can be
+preceded by a number `N`, meaning we want to find the `N`-th line that
+matches the search. I can see this being useful with `N=2` in case you
+want to find the first next occurrence of a word that appears on the
+current screen. But it is probably easier to just rely on the `n` and `N`
+commands, which simply repeat the previous search, in the same or opposite
+direction respectively; for example, using `N` after a `?` search searches
+for the same pattern *forward*.
+
+The next group of commands is used to move between different files: `:e`
+to open a new one, `:n` for the next file and `:p` for the previous.
+`:t` is used to move between the aforementioned (but not explained) tags.
+
+If you are using more to view a file, the command `v` can be used to edit it,
+using the editor vi(1) by default.
+
+And finally
+
+```
+q | :q | ZZ Exits more.
+```
+
+The last sections are fairly short, but worth skimming through.
+
+The ENVIRONMENT section explains that more can read some environment
+variables to change its behavior. In my opionion the most interesting
+ones are `EDITOR`, which changes the editor to be used with the `v`
+command, and `MORE`, which can be used to set default options for more.
+
+An interesting example in the EXAMPLES section:
+
+```
+Examine several manual pages, starting from the options description in
+the DESCRIPTION section:
+
+ $ more -p '/DESCRIPTION
+ > /options
+ > ' *.1
+```
+
+And a word of warning from the STANDARDS section:
+
+```
+The more utility is compliant with the IEEE Std 1003.1-2008 ("POSIX.1") specification,
+though its presence is optional.
+```
+
+This means that, unfortunately, when dealing with some more obscure POSIX
+operating system you may not have the luxury of a pager program. Too bad.
+
+## Conclusions
+
+It is worth noting that the more(1) manual page states
+
+```
+The present implementation is actually less(1) in disguise.
+```
+
+In practice this means that in OpenBSD, even when using more, one can
+make full use of the extra features of less described in its manual
+page. One of the few differences is how certain options are interpreted.
+
+I originally planned to write about less(1), but I was, as the fictional
+*you* in the nuclear bunker, overwhelmed by the amount of options
+available. Most of them are either quite technical or just change
+slightly the behavior of the pager. Some can be nice, but definitely
+not necessary (e.g. `-P` to change the prompt).
+
+I don't see myself using any of the extra features described in the less(1)
+man page, with the notable exception of the `|` (pipe) command, which
+can be used to pipe arbitrary portions of the current file to an external
+command. But apart from this I could easily live in the pre-1985 era.
+
+See you next time!
diff --git a/src/blog/blog.md b/src/blog/blog.md
@@ -2,6 +2,7 @@
[RSS Feed](feed.xml)
+* 2022-06-08 [The man page reading club: more(1)](2022-06-08-more)
* 2022-06-04 [The gemini protocol](2022-06-04-gemini)
* 2022-05-29 [The man page reading club: man(1)](2022-05-29-man)
* 2022-05-21 [Blogs](2022-05-21-blogs)
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: more(1)</title>
+<link>https://sebastiano.tronto.net/blog/2022-06-08-more</link>
+<description>The man page reading club: more(1)</description>
+<pubDate>2022-06-08</pubDate>
+</item>
+
+<item>
<title>The gemini protocol</title>
<link>https://sebastiano.tronto.net/blog/2022-06-04-gemini</link>
<description>The gemini protocol</description>
diff --git a/src/style-2.css b/src/style-2.css
@@ -1,105 +0,0 @@
-header nav table {
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-
-.logo img {
- max-width: 3em;
- margin: 0 0 0 0;
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-.links {
- text-align: right;
- font-weight: bold;
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- font-style: italic;
- width: 100%;
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-.hosted {
- text-align: right;
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-body {
- margin: auto 8px 20px 8px;
-}
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-img {
- display: block;
- margin-left: auto;
- margin-right: auto;
- max-width: 100%;
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-
-code {
- background-color: #eeeeee;
- padding: 2px;
-}
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-pre {
- background-color: #eeeeee;
- border: 2px solid;
- padding: 6px;
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-
-#blob {
- background: #ffffff;
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- color: #0f2899;
- text-decoration: none;
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-.links a {
- font-weight: bold;
- color: black;
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-.hosted a,
-.contact a {
- font-weight: bold;
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-
-a:hover {
- text-decoration: underline;
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-
-html {
- margin: 1em auto;
- max-width: 42em;
-}
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-h1 {
- text-align: center;
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-td h1 {
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- min-width: 33px;
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diff --git a/src/style-3.css b/src/style-3.css
@@ -0,0 +1,109 @@
+header nav table {
+ width: 100%;
+}
+
+.logo img {
+ max-width: 3em;
+ margin: 0 0 0 0;
+}
+
+.links {
+ text-align: right;
+ font-weight: bold;
+}
+
+footer table {
+ font-style: italic;
+ width: 100%;
+}
+
+.hosted {
+ text-align: right;
+}
+
+body {
+ margin: auto 8px 20px 8px;
+}
+
+img {
+ display: block;
+ margin-left: auto;
+ margin-right: auto;
+ max-width: 100%;
+}
+
+code {
+ background-color: #eeeeee;
+ padding: 2px;
+}
+
+pre code {
+ padding: 0px;
+}
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+pre {
+ background-color: #eeeeee;
+ border: 2px solid;
+ padding: 6px;
+}
+
+#blob {
+ background: #ffffff;
+ border: none;
+}
+
+a {
+ color: #0f2899;
+ text-decoration: none;
+}
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+.links a {
+ font-weight: bold;
+ color: black;
+}
+
+.hosted a,
+.contact a {
+ font-weight: bold;
+}
+
+a:hover {
+ text-decoration: underline;
+}
+
+html {
+ margin: 1em auto;
+ max-width: 42em;
+}
+
+h1 {
+ text-align: center;
+}
+
+td h1 {
+ text-align: left;
+ font-size: 1.5em;
+}
+
+table {
+ width: 100%;
+}
+
+#files td {
+ font-family: monospace;
+ font-size: 1.2em;
+ min-width: 7em;
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+
+#log tr:hover td,
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+ background-color: #eeeeee;
+}
+
+.url td {
+ font-family: monospace;
+}
+
+table tr td a img {
+ min-width: 33px;
+}
diff --git a/top.html b/top.html
@@ -3,7 +3,7 @@
<head>
<title> TITLE | Sebastiano Tronto </title>
<meta name="viewport" content="width=device-width" />
- <link rel="stylesheet" type="text/css" href="/style-2.css">
+ <link rel="stylesheet" type="text/css" href="/style-3.css">
<link rel="icon" href="/favicon.png">
<meta charset="utf-8">
</head>
