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man: use paragraphs in descriptions of /tmp and /var/tmp

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We have three somewhat separate ideas: what the directory is for, what $TMPDIR is for, and security considerations.
Let's use paragraphs.

Also, conjunctions in titles aren't capitalized usually.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2020-10-03 11:51:49 +02:00
parent 278c13431b
commit 422128b46d
2 changed files with 31 additions and 26 deletions
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4
docs/TEMPORARY_DIRECTORIES.md
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@ -1,10 +1,10 @@
---
title: Using /tmp/ And /var/tmp/ Safely
title: Using /tmp/ and /var/tmp/ Safely
category: Interfaces
layout: default
---
# Using `/tmp/` And `/var/tmp/` Safely
# Using `/tmp/` and `/var/tmp/` Safely
`/tmp/` and `/var/tmp/` are two world-writable directories Linux systems
provide for temporary files. The former is typically on `tmpfs` and thus

53
man/file-hierarchy.xml
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@ -127,20 +127,23 @@
<term><filename>/tmp/</filename></term>
<listitem><para>The place for small temporary files. This directory is usually mounted as a
<literal>tmpfs</literal> instance, and should hence not be used for larger files. (Use
<filename>/var/tmp/</filename> for larger files.) Since the directory is accessible to other users of
the system, it is essential that this directory is only written to with the <citerefentry
project='man-pages'><refentrytitle>mkstemp</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry
project='man-pages'><refentrytitle>mkdtemp</refentrytitle><manvolnum>3</manvolnum></citerefentry> and
related calls. This directory is usually flushed at boot-up. Also, files that are not accessed within
a certain time are usually automatically deleted. If applications find the environment variable
<varname>$TMPDIR</varname> set, they should prefer using the directory specified in it over directly
referencing <filename>/tmp/</filename> (see <citerefentry
<filename>/var/tmp/</filename> for larger files.) This directory is usually flushed at boot-up. Also,
files that are not accessed within a certain time may be automatically deleted.</para>
<para>If applications find the environment variable <varname>$TMPDIR</varname> set, they should use
the directory specified in it instead of <filename>/tmp/</filename> (see <citerefentry
project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry> and
<ulink url="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03">IEEE
Std 1003.1</ulink> for details). For further details about this directory, see <ulink
url="https://systemd.io/TEMPORARY_DIRECTORIES">Using /tmp/ And /var/tmp/
Safely</ulink>.</para></listitem>
Std 1003.1</ulink> for details).</para>
<para>Since <filename>/tmp/</filename> is accessible to other users of the system, it is essential
that files and subdirectories under this directory are only created with <citerefentry
project='man-pages'><refentrytitle>mkstemp</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry
project='man-pages'><refentrytitle>mkdtemp</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
and similar calls. For more details, see <ulink url="https://systemd.io/TEMPORARY_DIRECTORIES">Using
/tmp/ and /var/tmp/ Safely</ulink>.</para>
</listitem>
</varlistentry>
</variablelist>
@ -334,20 +337,22 @@
<term><filename>/var/tmp/</filename></term>
<listitem><para>The place for larger and persistent temporary files. In contrast to
<filename>/tmp/</filename>, this directory is usually mounted from a persistent physical file system
and can thus accept larger files. (Use <filename>/tmp/</filename> for smaller files.) This directory
is generally not flushed at boot-up, but time-based cleanup of files that have not been accessed for
a certain time is applied. The same security restrictions as with <filename>/tmp/</filename> apply,
and hence only <citerefentry
and can thus accept larger files. (Use <filename>/tmp/</filename> for small ephemeral files.) This
directory is generally not flushed at boot-up, but time-based cleanup of files that have not been
accessed for a certain time is applied.</para>
<para>If applications find the environment variable <varname>$TMPDIR</varname> set, they should use
the directory specified in it instead of <filename>/var/tmp/</filename> (see <citerefentry
project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
details).</para>
<para>The same security restrictions as with <filename>/tmp/</filename> apply: <citerefentry
project='man-pages'><refentrytitle>mkstemp</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry
project='man-pages'><refentrytitle>mkdtemp</refentrytitle><manvolnum>3</manvolnum></citerefentry> or
similar calls should be used to make use of this directory. If applications find the environment
variable <varname>$TMPDIR</varname> set, they should prefer using the directory specified in it over
directly referencing <filename>/var/tmp/</filename> (see <citerefentry
project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
details). For further details about this directory, see <ulink
url="https://systemd.io/TEMPORARY_DIRECTORIES">Using /tmp/ And /var/tmp/
Safely</ulink>.</para></listitem>
project='man-pages'><refentrytitle>mkdtemp</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
and similar calls should be used. For further details about this directory, see <ulink
url="https://systemd.io/TEMPORARY_DIRECTORIES">Using /tmp/ and /var/tmp/ Safely</ulink>.</para>
</listitem>
</varlistentry>
</variablelist>