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+---
+title: "Maintaining a Server"
+date: 2021-06-29
+tags: ["server"]
+---
+
+Here are some important topics you should be familiar with whenever you
+are managing a server.
+
+## Keep packages up to date. {#update}
+
+All GNU/Linux distributions use package managers to easily be able to
+install and update packages without manually downloading them. On
+Debian, which we use here for these tutorial the package manager is
+`apt-get` or `apt` for short.
+
+It\'s a good idea to use `apt` to keep your software reasonably up to
+date.
+
+```sh
+apt update
+apt upgrade
+```
+
+Not only do up-to-date packages often come with more features, but they
+can also fix any possible security bugs.
+
+## Troubleshooting general problems
+
+Often when you are installing something new, you might miss a step and
+run into an error, so it\'s important to know how to check and see what
+errors have happened on your computer.
+
+On Debian and other GNU/Linux distributions that use systemd (most of
+them), you can use the command `journalctl` to look at the system\'s
+general log. You will probably want to run `journalctl -xe` as the `-x`
+and `-e` as that gives the most information and starts you at the bottom
+of the log to see the most recent errors.
+
+Some programs do not use this system log, but have their own logs stored
+in `/var/log/`, or sometimes it\'s more convenient to look at a specific
+program\'s log to see only its issues.
+
+For example, we can see that in `/var/log/nginx/`, nginx produces both
+`error` and `access` files. The `access` files show you all the times
+people connect to files on your server and much more. We can look at the
+most recent errors by running:
+
+```sh
+tail -n 25 /var/log/nginx/error.log
+```
+
+The command `tail -n 25` means \"show me the last 25 lines of this
+file.\" You can replace that with `less` to browse the whole file. In
+`less`, navigate with arrows or vim-keys and exit with `q`.
+
+### systemctl
+
+Another tool on systemd distributions is `systemctl`. At a basic level,
+use `systemctl status put-service-name-here` to see if a system service
+is running and its most recent log. But there\'s much more to
+`systemctl`.
+
+For example, you can run `systemctl stop nginx` to stop NginX and
+`systemctl start nginx` to start it back up (or use `restart` for both).
+When you make changes to a program\'s configuration files, `reload` well
+make them reload them. If you no longer want a service to start when the
+system is rebooted, use `disable`, or conversely, to make a service
+start on reboot use `enable`.
+
+## Finding Files
+
+Especially if you\'re new to how a GNU/Linux system is arranged, you
+might need help finding files. To find program-related files, you can
+just use `whereis`:
+
+```sh
+$ whereis nginx
+nginx: /usr/sbin/nginx /usr/lib/nginx /etc/nginx /usr/share/nginx /usr/share/man/man8/nginx.8.gz
+```
+
+This command lists the directories related to that program. For example,
+`/etc/nginx` is where the configuration files are and `/usr/share/nginx`
+is where the library and module-like files are.
+
+But `whereis` can be used only with installed programs. A more general
+tool is the pair of `updatedb` and `locate`.
+
+`updatedb` is a command that quickly indexes every file and directory on
+your computer. Then you can run `locate` to find a file containing a
+given name. After running `updatedb`, try running `locate nginx` to find
+all files with \"nginx\" in their name.
+
+You can make your search more specific by chaining other Unix commands
+through pipes. For example, `grep` takes input and returns only lines
+that match an extra argument. In the example below, we `locate` all
+files with \"nginx\" in the name, but we use `grep` to only show us
+those with the word \"available\" in them.
+
+```sh
+root@sich:~# locate nginx | grep available
+/etc/nginx/modules-available
+/etc/nginx/sites-available
+/etc/nginx/sites-available/default
+/etc/nginx/sites-available/sich
+/usr/share/nginx/modules-available
+/usr/share/nginx/modules-available/mod-http-auth-pam.conf
+/usr/share/nginx/modules-available/mod-http-dav-ext.conf
+/usr/share/nginx/modules-available/mod-http-echo.conf
+/usr/share/nginx/modules-available/mod-http-geoip.conf
+/usr/share/nginx/modules-available/mod-http-image-filter.conf
+/usr/share/nginx/modules-available/mod-http-subs-filter.conf
+/usr/share/nginx/modules-available/mod-http-upstream-fair.conf
+/usr/share/nginx/modules-available/mod-http-xslt-filter.conf
+/usr/share/nginx/modules-available/mod-mail.conf
+/usr/share/nginx/modules-available/mod-stream.conf
+```
+
+`updatedb` is an ideal candidate for a [cronjob](/cron) so you
+don\'t have to worry about running each time. For example, adding the
+following to your crontab will run `updatedb` every 30 minutes:
+
+```sh
+*/30 * * * * /usr/bin/updatedb
+```