Linux Administration¶
Core shell commands and concepts for administering Linux hosts.
Why It Matters¶
Linux administration runs on the command line, so fluency with the shell, job control, and the common information commands is what makes the work efficient. These are the building blocks everything else sits on.
Reference¶
Shell Operators¶
| Operator | Meaning |
|---|---|
& |
Run a command in the background |
&& |
Run the next command only if the previous succeeded |
> |
Redirect output to a file (overwrite) |
>> |
Redirect output to a file (append) |
\| |
Pipe output of one command into another |
Common Commands¶
ls -lh # long listing with human-readable sizes
ps aux # running processes
top # live process view
ip a # interfaces and addresses
systemctl start <unit> # start a service
python3 -m http.server # quick local web server
Job Control¶
| Action | Command |
|---|---|
| Suspend foreground process | Ctrl + Z |
| Start in background | append & |
| Bring job to foreground | fg |
| Kill a job / process | kill %1 / kill <pid> |
System Information¶
cat /etc/os-release # distribution and version
grep "^$USER" /etc/passwd # your login shell
curl ifconfig.me # public IP
SSH keys live in ~/.ssh/ by default (for example ~/.ssh/id_rsa).
Cron¶
Scheduling reference: crontab.guru explains any cron expression, and crontab-generator.org builds one.
How I Use It¶
I live in the shell for Linux work and lean on systemctl, ps, and ip for day-to-day state. crontab.guru is my go-to for getting a cron schedule right the first time, and vim.rtorr.com is a handy Vim cheatsheet when editing configs on a remote host.