logger
logger # Write to system logs using syslogd, rsyslogd, systemd-journald, etc.
linux
Package Management
Package Management # Red Hat Family # rpm RHEL, CentOS, Fedora, Rocky, Alma # dnf SUSE # zypper Debian Family # dpkg apt Arch Linux Family # pacman
pacman
pacman #
Performance & Optimization
Performance & Optimization # Resources # Explanation of what load averages really means Commands you should run in the first 60 seconds on a misbehaving server In-depth analysis of Linux Performance tools 30 Linux monitoring tools every sysadmin should know Notes # Source Slides from presentation It’s important to have a methodology. ...
ps
ps # ps (1) - report a snapshot of the current processes. Print all process information with BSD syntax: ps aux Print process information for all processes in full format: ps -ef Print process information for all processes in extra full format, long format: ps -eFl Format ps output: ps -o comm,pid,ppid,user Print processes matching a specific command name: ps -C sshd List all processes owned by a specific user: ...
Regular Expressions
Symbolic notations used to identify patterns in text literal characters # metacharacters # ^ $ . [ ] { } - ? * + ( ) | \ Most of these have meaning to the shell and must be quoted Metacharacters Character Meaning Usage . Any character ^ Anchor Beginning of the line $ End of the line [ ] Bracket Expression Specify a set of characters at a position ‘^’ negation within brackets ‘-’ range of something within brackets POSIX Character Classes ...
RHCSA Notes
RHCSA Notes # Basic System Management # Linux Filesystem File Permissions Linux Utilities User Management Local User Authentication Files Configuring Networking # 202404240919-private-network 202010261345-subnetting Operating Running Systems # Package Management 20220525072458-rpm 202403200951-dnf 202405121207-systemd 202405081005-cron
Servers
Email Webservers
Shell Startup
Shell Startup # Shell Startup Files # System-wide Shell Startup Files # /etc/bashrc /etc/profile /etc/profile.d Per-user Shell Startup Files # .bashrc .bash_profile
SSH client
SSH Client #