pwd<\/code><\/h3>\nPrint Working Directory<\/strong><\/p>\npwd\r\n<\/code><\/pre>\nShows your current directory.<\/p>\n
ls<\/code><\/h3>\nList Contents<\/strong><\/p>\nls # List files \r\nls -l # Long format \r\nls -a # Include hidden files \r\n<\/code><\/pre>\ncd<\/code><\/h3>\nChange Directory<\/strong><\/p>\ncd \/etc # Absolute path \r\ncd .. # Go up one level \r\ncd ~ # Go to home directory \r\n<\/code><\/pre>\nmkdir<\/code> & rmdir<\/code><\/h3>\nCreate and Remove Directories<\/strong><\/p>\nmkdir new_folder \r\nrmdir old_folder \r\n<\/code><\/pre>\n\u00a02. File Management<\/h2>\n
Manipulating files is an everyday task for sysadmins.<\/p>\n
touch<\/code><\/h3>\nCreate Empty File<\/strong><\/p>\ntouch test.txt\r\n<\/code><\/pre>\ncp<\/code>, mv<\/code>, rm<\/code><\/h3>\nCopy, Move, and Remove Files<\/strong><\/p>\ncp file.txt \/backup\/ \r\nmv file.txt newname.txt \r\nrm file.txt # Use with caution!\r\n<\/code><\/pre>\ncat<\/code>, less<\/code>, head<\/code>, tail<\/code><\/h3>\nView File Contents<\/strong><\/p>\ncat file.txt \r\nless file.txt \r\nhead -n 10 file.txt # First 10 lines \r\ntail -f \/var\/log\/syslog # Live log view \r\n<\/code><\/pre>\n3. User and Permission Management<\/h2>\n
Controlling access is critical for server security.<\/p>\n
adduser<\/code> \/ useradd<\/code><\/h3>\nCreate New User<\/strong><\/p>\nadduser johndoe\r\n<\/code><\/pre>\npasswd<\/code><\/h3>\nChange Password<\/strong><\/p>\npasswd johndoe\r\n<\/code><\/pre>\nusermod<\/code><\/h3>\nModify User Account<\/strong><\/p>\nusermod -aG sudo johndoe # Add to sudoers \r\n<\/code><\/pre>\nchmod<\/code> \/ chown<\/code><\/h3>\nChange Permissions and Ownership<\/strong><\/p>\nchmod 755 script.sh \r\nchown user:group file.txt\r\n<\/code><\/pre>\n4. System Monitoring<\/h2>\n
These commands help you track performance and spot issues.<\/p>\n
top<\/code> \/ htop<\/code><\/h3>\nLive Process Monitor<\/strong><\/p>\ntop\r\n<\/code><\/pre>\nFor a friendlier interface, install htop<\/code>:<\/p>\nsudo apt install htop\r\nhtop\r\n<\/code><\/pre>\ndf -h<\/code><\/h3>\nDisk Space Usage<\/strong><\/p>\ndf -h\r\n<\/code><\/pre>\ndu -sh<\/code><\/h3>\nDirectory Size Summary<\/strong><\/p>\ndu -sh \/var\/log\r\n<\/code><\/pre>\nfree -h<\/code><\/h3>\nMemory Usage<\/strong><\/p>\nfree -h\r\n<\/code><\/pre>\nuptime<\/code><\/h3>\nSystem Load and Running Time<\/strong><\/p>\nuptime\r\n<\/code><\/pre>\n
\n\u00a05. Network Management<\/h2>\n
Server connectivity is everything\u2014monitor it with these tools.<\/p>\n
ip a<\/code> or ifconfig<\/code><\/h3>\nView Network Interfaces<\/strong><\/p>\nip a\r\n<\/code><\/pre>\nping<\/code><\/h3>\nTest Connectivity<\/strong><\/p>\nping google.com\r\n<\/code><\/pre>\nnetstat<\/code> or ss<\/code><\/h3>\nList Network Connections<\/strong><\/p>\nss -tuln\r\n<\/code><\/pre>\ntraceroute<\/code><\/h3>\nTrace Packet Path<\/strong><\/p>\ntraceroute google.com\r\n<\/code><\/pre>\ncurl<\/code> & wget<\/code><\/h3>\nDownload Files or Check Web Status<\/strong><\/p>\ncurl -I https:\/\/example.com \r\nwget https:\/\/example.com\/file.zip\r\n<\/code><\/pre>\n6. Package Management<\/h2>\n
Installing and updating software is common in server maintenance.<\/p>\n
For Debian\/Ubuntu (APT):<\/h3>\nsudo apt update \r\nsudo apt upgrade \r\nsudo apt install nginx \r\nsudo apt remove apache2\r\n<\/code><\/pre>\nFor CentOS\/RHEL (YUM or DNF):<\/h3>\nsudo yum update \r\nsudo yum install httpd \r\nsudo dnf install nginx\r\n<\/code><\/pre>\n
\n7. Searching and Filtering<\/h2>\n
Find files or filter logs with precision.<\/p>\n
find<\/code><\/h3>\nSearch for Files<\/strong><\/p>\nfind \/ -name \"config.php\"\r\n<\/code><\/pre>\ngrep<\/code><\/h3>\nText Pattern Search<\/strong><\/p>\ngrep \"error\" \/var\/log\/syslog\r\n<\/code><\/pre>\nUse with pipes:<\/p>\n
cat log.txt | grep \"404\"\r\n<\/code><\/pre>\nlocate<\/code><\/h3>\nFast File Lookup<\/strong><\/p>\nsudo updatedb \r\nlocate php.ini\r\n<\/code><\/pre>\n8. Log File Management<\/h2>\n
Monitoring logs helps you detect errors and intrusions.<\/p>\n
journalctl<\/code><\/h3>\nSystemd Log Viewer<\/strong><\/p>\njournalctl -xe\r\n<\/code><\/pre>\nCommon Log Files:<\/h3>\n\n\/var\/log\/syslog<\/code> \u2013 system messages<\/li>\n\/var\/log\/auth.log<\/code> \u2013 SSH and user activity<\/li>\n\/var\/log\/apache2\/<\/code> \u2013 Apache logs<\/li>\n\/var\/log\/nginx\/<\/code> \u2013 NGINX logs<\/li>\n<\/ul>\ntail -f<\/code><\/h3>\nWatch Logs in Real Time<\/strong><\/p>\ntail -f \/var\/log\/nginx\/error.log\r\n<\/code><\/pre>\n9. Process and Service Management<\/h2>\n
Start, stop, and inspect services.<\/p>\n
systemctl<\/code><\/h3>\nManage Services on Systemd Systems<\/strong><\/p>\nsudo systemctl start nginx \r\nsudo systemctl stop apache2 \r\nsudo systemctl restart mysql \r\nsudo systemctl status ssh\r\n<\/code><\/pre>\nps<\/code> & kill<\/code><\/h3>\nList and Terminate Processes<\/strong><\/p>\nps aux | grep nginx \r\nkill 1234 # Kill process by PID \r\nkill -9 1234 # Force kill\r\n<\/code><\/pre>\n10. SSH & Remote Management<\/h2>\n
Connect and control servers remotely.<\/p>\n
ssh<\/code><\/h3>\nConnect to Remote Server<\/strong><\/p>\nssh user@yourserver.com\r\n<\/code><\/pre>\nscp<\/code><\/h3>\nSecure File Copy<\/strong><\/p>\nscp file.txt user@host:\/path\/\r\n<\/code><\/pre>\nBonus: Time-Saving Shortcuts<\/h2>\n
\n\n\n| Shortcut<\/th>\n | Description<\/th>\n<\/tr>\n<\/thead>\n |
\n\n!!<\/code><\/td>\n| Run last command again<\/td>\n<\/tr>\n | \n!n<\/code><\/td>\n| Run command number n from history<\/td>\n<\/tr>\n | \nCtrl + R<\/code><\/td>\n| Reverse search through command history<\/td>\n<\/tr>\n | \nhistory<\/code><\/td>\n| Show command history<\/td>\n<\/tr>\n | \nalias<\/code><\/td>\nCreate command shortcut<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\nalias ll='ls -lah'\r\n<\/code><\/pre>\nSafety Tips for Admins<\/h2>\n\n- Never run random commands with
sudo<\/code> unless you understand them.<\/li>\n- Use
--dry-run<\/code> options if available (e.g., rsync --dry-run<\/code>)<\/li>\n- Regularly back up config files before editing them.<\/li>\n
- Use a non-root user with
sudo<\/code> privileges for daily tasks.<\/li>\n- Set up a firewall (
ufw<\/code> or firewalld<\/code>) and fail2ban for security.<\/li>\n<\/ul>\nSample Workflow: Updating Your Server Securely<\/h2>\n# Step 1: Connect\r\nssh user@yourserver.com\r\n\r\n# Step 2: Update system\r\nsudo apt update && sudo apt upgrade\r\n\r\n# Step 3: Check disk space\r\ndf -h\r\n\r\n# Step 4: Monitor live logs\r\ntail -f \/var\/log\/syslog\r\n\r\n# Step 5: Reboot if needed\r\nsudo reboot\r\n<\/code><\/pre>\n
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