{"id":358,"date":"2025-03-03T10:02:40","date_gmt":"2025-03-03T10:02:40","guid":{"rendered":"http:\/\/www.scmgalaxy.com\/tutorials\/2014\/07\/21\/linux-commands-for-administrator\/"},"modified":"2025-03-03T10:02:40","modified_gmt":"2025-03-03T10:02:40","slug":"linux-commands-for-administrator","status":"publish","type":"post","link":"https:\/\/www.devopsschool.com\/blog\/linux-commands-for-administrator\/","title":{"rendered":"Linux Tutorials: Commands for Linux Administrator"},"content":{"rendered":"\n
\"\"<\/figure>\n\n\n\n

1. sudo<\/code> – Execute commands with elevated privileges, a fundamental for system administration.<\/h1>\n\n\n\n

2. useradd<\/code> – Create a new user account, essential for managing user access.<\/h1>\n\n\n\n

3. usermod<\/code> – Modify a user account, useful for changing account properties.<\/h1>\n\n\n\n

4. userdel<\/code> – Delete a user account, important for managing system access.<\/h1>\n\n\n\n

5. groupadd<\/code> – Add a new group, crucial for managing group permissions.<\/h1>\n\n\n\n

6. groupmod<\/code> – Modify a group, allows changing group attributes.<\/h1>\n\n\n\n

7. groupdel<\/code> – Delete a group, used for removing group access.<\/h1>\n\n\n\n

8. chown<\/code> – Change file owner and group, vital for managing file permissions.<\/h1>\n\n\n\n

9. chmod<\/code> – Change file access permissions, key for securing system files.<\/h1>\n\n\n\n

10. chgrp<\/code> – Change group ownership, important for managing group file access.<\/h1>\n\n\n\n

11. passwd<\/code> – Update a user\u2019s password, critical for account security.<\/h1>\n\n\n\n

12. adduser<\/code> – Add a user account (more interactive than useradd<\/code>).<\/h1>\n\n\n\n

13. deluser<\/code> – Delete a user account (more user-friendly than userdel<\/code>).<\/h1>\n\n\n\n

14. visudo<\/code> – Edit the sudoers file, crucial for configuring sudo privileges.<\/h1>\n\n\n\n

15. systemctl<\/code> – Control and manage systemd units, essential for managing services.<\/h1>\n\n\n\n
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# 1. Start a service immediately<\/span>\nsystemctl start serviceName.service\n\n# 2. Stop a service immediately<\/span>\nsystemctl stop serviceName.service\n\n# 3. Restart a service<\/span>\nsystemctl restart serviceName.service\n\n# 4. Show the status of a service<\/span>\nsystemctl status serviceName.service\n\n# 5. Enable a service to start on boot<\/span>\nsystemctl enable serviceName.service\n\n# 6. Disable a service from starting on boot<\/span>\nsystemctl disable serviceName.service\n\n# 7. Check whether a service is enabled<\/span>\nsystemctl is-enabled serviceName.service\n\n# 8. Reload the service configuration without interrupting operations<\/span>\nsystemctl reload serviceName.service\n\n# 9. View all running services<\/span>\nsystemctl list<\/span>-units --type=service --state=running\n\n# 10. Mask a service to prevent it from being started, manually or automatically<\/span>\nsystemctl mask serviceName.service\n<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
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16. journalctl<\/code> – Query and display messages from the journal, used for system logging.<\/h1>\n\n\n\n
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# 1. Display all log messages<\/span>\njournalctl\n\n# 2. Display log messages from the current boot<\/span>\njournalctl -b\n\n# 3. Display log messages from a previous boot<\/span>\njournalctl -b -1<\/span>\n\n# 4. Follow the journal live (similar to tail -f)<\/span>\njournalctl -f\n\n# 5. Show kernel messages (similar to dmesg)<\/span>\njournalctl -k\n\n# 6. Filter log messages by a specific unit<\/span>\njournalctl -u nginx.service\n\n# 7. Filter log messages by priority (0=emerg to 7=debug)<\/span>\njournalctl -p err\n\n# 8. Show log messages in a specific time range<\/span>\njournalctl --since \"2023-01-01\"<\/span> --until \"2023-01-02\"<\/span>\n\n# 9. Show log messages for a specific process ID<\/span>\njournalctl _PID=1234<\/span>\n\n# 10. Combine filters, e.g., show error messages for a specific unit since yesterday<\/span>\njournalctl -u apache2.service -p err --since yesterday\n<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
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17. top<\/code> – Display task manager, important for monitoring system performance.<\/h1>\n\n\n\n
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# Note:<\/span> Most examples are intended to be used within top's interactive mode<\/span>\n\n# 1. Start top with a specific delay between updates in seconds<\/span>\ntop -d 5<\/span>\n\n# 2. Display top for a specific user's processes<\/span>\ntop -u username<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
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18. htop<\/code> – Interactive process viewer, an enhanced alternative to top<\/code>.<\/h1>\n\n\n\n
19. df<\/code> – Report file system disk space usage, crucial for monitoring disk usage.<\/h1>\n\n\n\n
20. du<\/code> – Estimate file space usage, useful for managing disk space.<\/h1>\n\n\n\n
21. free<\/code> – Display memory usage, important for memory management.<\/h1>\n\n\n\n
22. vmstat<\/code> – Report virtual memory statistics, helpful for performance monitoring.<\/h1>\n\n\n\n
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# 1. Basic usage - Display virtual memory statistics<\/span>\nvmstat\n\n# 2. Display vmstat output with a specific interval and count<\/span>\n# This will display the report every 2 seconds, 5 times<\/span>\nvmstat 2<\/span> 5<\/span>\n\n# 3. Show memory statistics in megabytes<\/span>\nvmstat -S M\n\n# 4. Display additional information including slab info<\/span>\nvmstat -m\n\n# 5. Display disk statistics<\/span>\nvmstat -d\n\n# 6. Display partition statistics<\/span>\nvmstat -p \/dev\/sda1\n\n# 7. Display event counter statistics<\/span>\nvmstat -s\n\n# 8. Show CPU activity as an average since the last reboot<\/span>\nvmstat -a\n\n# 9. Include timestamps in the output<\/span>\nvmstat -t\n\n# 10. Display statistics with a delay and include timestamp<\/span>\n# This will show the report every 3 seconds with the timestamp included<\/span>\nvmstat 3<\/span> -t\n<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
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23. iostat<\/code> – Monitor system input\/output device loading, used for diagnosing performance issues.<\/h1>\n\n\n\n
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# 1. Basic usage - Display the CPU and device utilization report<\/span>\niostat\n\n# 2. Display the report at 2-second intervals<\/span>\niostat 2<\/span>\n\n# 3. Display the extended statistics with more details<\/span>\niostat -x\n\n# 4. Display disk utilization report every 2 seconds, 3 times<\/span>\niostat 2<\/span> 3<\/span>\n\n# 5. Show only CPU statistics<\/span>\niostat -c\n\n# 6. Show only device utilization statistics<\/span>\niostat -d\n\n# 7. Display statistics in megabytes per second<\/span>\niostat -m\n\n# 8. Show extended statistics with device utilization, refreshing every 5 seconds indefinitely<\/span>\niostat -dx 5<\/span>\n\n# 9. Display statistics for a specific device (e.g., sda)<\/span>\niostat -d sda\n\n# 10. Display persistent device names and extended statistics<\/span>\niostat -Nx\n<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
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24. netstat<\/code> – Display network connections, routing tables, interface statistics, masquerade connections, and multicast memberships.<\/h1>\n\n\n\n
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# 1. List all ports (both listening and non-listening ports)<\/span>\nnetstat -a\n\n# 2. List all listening ports<\/span>\nnetstat -l\n\n# 3. Display TCP connections<\/span>\nnetstat -t\n\n# 4. Display UDP connections<\/span>\nnetstat -u\n\n# 5. Show statistics by protocol (e.g., TCP, UDP)<\/span>\nnetstat -s\n\n# 6. Display listening TCP ports with numeric addresses and don't resolve names<\/span>\nnetstat -lnt\n\n# 7. Display listening UDP ports with numeric addresses and don't resolve names<\/span>\nnetstat -lnu\n\n# 8. Show the routing table<\/span>\nnetstat -r\n\n# 9. Display all sockets, including listening and non-listening, without resolving names<\/span>\nnetstat -an\n\n# 10. Show which process is using a particular port<\/span>\nnetstat -tulnp\n<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
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25. ss<\/code> – Another utility to investigate sockets, replaces netstat<\/code>.<\/h1>\n\n\n\n
26. ip<\/code> – Show \/ manipulate routing, devices, policy routing and tunnels, central for network configuration.<\/h1>\n\n\n\n
27. ifconfig<\/code> – Configure a network interface, traditionally used before ip<\/code>.<\/h1>\n\n\n\n
28. iptables<\/code> – Administer IPv4 packet filtering and NAT, key for firewall management.<\/h1>\n\n\n\n
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# 1. List all current iptables rules<\/span>\niptables -L\n\n# 2. Block traffic from a specific IP address<\/span>\niptables -A INPUT -s 192.168<\/span>.1<\/span>.100<\/span> -j DROP\n\n# 3. Allow SSH access from a specific IP address<\/span>\niptables -A INPUT -p tcp -s 192.168<\/span>.1<\/span>.100<\/span> --dport 22<\/span> -j ACCEPT\n\n# 4. Reject all incoming traffic but allow outgoing traffic<\/span>\niptables -P INPUT REJECT\niptables -P OUTPUT ACCEPT\n\n# 5. Allow traffic to a specific port (e.g., HTTP port 80)<\/span>\niptables -A INPUT -p tcp --dport 80<\/span> -j ACCEPT\n\n# 6. Delete all rules in a specific chain (e.g., INPUT chain)<\/span>\niptables -F INPUT\n\n# 7. Block all traffic from a specific subnet<\/span>\niptables -A INPUT -s 192.168<\/span>.1<\/span>.0<\/span>\/24<\/span> -j DROP\n\n# 8. Allow all incoming traffic on a specific interface (e.g., eth0)<\/span>\niptables -A INPUT -i eth0 -j ACCEPT\n\n# 9. Log dropped packets<\/span>\niptables -A INPUT -m limit --limit 5<\/span>\/min -j LOG --log-prefix \"iptables dropped: \"<\/span> --log-level 7<\/span>\n\n# 10. Save iptables rules to be loaded on boot<\/span>\niptables-save > \/etc\/iptables\/rules.v4\n<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
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29. firewalld<\/code> – Dynamically manage firewall with support for network zones.<\/h1>\n\n\n\n
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# 1. Start firewalld<\/span>\nsudo systemctl start firewalld\n\n# 2. Enable firewalld to start at boot<\/span>\nsudo systemctl enable firewalld\n\n# 3. Check the status of firewalld<\/span>\nsudo systemctl status firewalld\n\n# 4. Reload firewalld rules without losing state<\/span>\nsudo firewall-cmd --reload\n\n# 5. List all active zones<\/span>\nsudo firewall-cmd --get-active-zones\n\n# 6. Set the default zone<\/span>\nsudo firewall-cmd --set-default<\/span>-zone=public<\/span>\n\n# 7. Add a service to the default zone permanently<\/span>\nsudo firewall-cmd --permanent --add-service=http\n\n# 8. Open a port in the default zone permanently<\/span>\nsudo firewall-cmd --permanent --add-port=8080<\/span>\/tcp\n\n# 9. Remove a service from the default zone permanently<\/span>\nsudo firewall-cmd --permanent --remove-service=http\n\n# 10. List all rules in the default zone<\/span>\nsudo firewall-cmd --list<\/span>-all\n<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
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30. nftables<\/code> – Modern replacement for iptables, ip6tables, arptables, and ebtables.<\/h1>\n\n\n\n
31. crontab<\/code> – Schedule periodic background jobs, essential for automating tasks.<\/h1>\n\n\n\n
32. rsync<\/code> – Fast, versatile file copying tool, important for backups and synchronization.<\/h1>\n\n\n\n
33. tar<\/code> – Archive utility, used for packing and unpacking archive files.<\/h1>\n\n\n\n
34. gzip<\/code> \/ bzip2<\/code> – Compress or expand files, crucial for managing file sizes.<\/h1>\n\n\n\n
35. unzip<\/code> \/ zip<\/code> – Compress and decompress files in zip format.<\/h1>\n\n\n\n
36. mount<\/code> – Mount a filesystem, important for attaching storage devices.<\/h1>\n\n\n\n
37. umount<\/code> – Unmount file systems, counterpart to mount<\/code>.<\/h1>\n\n\n\n
38. fsck<\/code> – Check and repair a Linux filesystem, crucial for filesystem maintenance.<\/h1>\n\n\n\n
39. lvm<\/code> – Logical Volume Manager, essential for managing disk storage.<\/h1>\n\n\n\n
40. ssh<\/code> – Secure Shell, a protocol for secure remote login and other secure network services.<\/h1>\n\n\n\n
41. scp<\/code> – Secure copy (remote file copy program), used for secure file transfer.<\/h1>\n\n\n\n
42. sftp<\/code> – Secure File Transfer Program, another secure file transfer utility.<\/h1>\n\n\n\n
43. wget<\/code> – Non-interactive network downloader, used for downloading files from the web.<\/h1>\n\n\n\n
44. curl<\/code> – Tool to transfer data from or to a server, supports various protocols.<\/h1>\n\n\n\n
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# 1. Download a file<\/span>\ncurl -O http:\/\/example.com\/file.txt<\/span>\n\n# 2. Save the downloaded file with a specific filename<\/span>\ncurl -o newfilename.txt http:\/\/example.com\/file.txt<\/span>\n\n# 3. Use curl with a user agent<\/span>\ncurl -A \"Mozilla\/5.0\"<\/span> http:\/\/example.com<\/span>\n\n# 4. Send a GET request<\/span>\ncurl -X GET http:\/\/example.com<\/span>\n\n# 5. Send a POST request with data<\/span>\ncurl -X POST -d \"data=example\"<\/span> http:\/\/example.com\/post<\/span>\n\n# 6. Send a POST request with a file<\/span>\ncurl -X POST -F \"file=@localfile.txt\"<\/span> http:\/\/example.com\/upload<\/span>\n\n# 7. Pass a header to the HTTP request<\/span>\ncurl -H \"X-Custom-Header: value\"<\/span> http:\/\/example.com<\/span>\n\n# 8. Follow HTTP redirects<\/span>\ncurl -L http:\/\/example.com<\/span>\n\n# 9. Perform a basic HTTP authentication<\/span>\ncurl -u username:password http:\/\/example.com<\/span>\n\n# 10. Use verbose mode to see request\/response details<\/span>\ncurl -v http:\/\/example.com<\/span>\n\n# 11. Make a request to an HTTPS site that has a self-signed cert<\/span>\ncurl -k https:\/\/example.com<\/span>\n\n# 12. Resume a previous file transfer<\/span>\ncurl -C - -O http:\/\/example.com\/bigfile.zip<\/span>\n\n# 13. Limit the bandwidth for file download<\/span>\ncurl --limit-rate 100<\/span>K -O http:\/\/example.com\/bigfile.zip<\/span>\n\n# 14. Use a proxy for the HTTP request<\/span>\ncurl -x http:\/\/proxy-server:port http:\/\/example.com<\/span>\n\n# 15. Get the HTTP headers of a URL<\/span>\ncurl -I http:\/\/example.com<\/span>\n\n# 16. Use cookies with your request<\/span>\ncurl -b \"name=value\"<\/span> http:\/\/example.com<\/span>\n\n# 17. Store server's response cookies into a file<\/span>\ncurl -c cookies.txt http:\/\/example.com<\/span>\n\n# 18. Send a custom request method<\/span>\ncurl -X PUT http:\/\/example.com<\/span>\n\n# 19. Use IPv6 for the request<\/span>\ncurl -6<\/span> http:\/\/example.com<\/span>\n\n# 20. Include both request headers and response in the output<\/span>\ncurl -i http:\/\/example.com<\/span>\n<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
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1. sudo – Execute commands with elevated privileges, a fundamental for system administration. 2. useradd – Create a new user account, essential for managing user access. 3. usermod – Modify a user account, useful for changing account properties. 4. userdel – Delete a user account, important for managing system access. 5. groupadd – Add a…<\/p>\n","protected":false},"author":1,"featured_media":3667,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_kad_post_transparent":"","_kad_post_title":"","_kad_post_layout":"","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"_kad_post_classname":"","_joinchat":[],"footnotes":""},"categories":[4957],"tags":[1996,1993,378,460,2003,1994,1995,1999,1998,1997,2000,2002,2001],"class_list":["post-358","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-linux","tag-admin-linux-commands","tag-administrator","tag-commands","tag-linux","tag-linux-admin-commands-reference","tag-linux-commands","tag-linux-commands-for-administrators","tag-linux-commands-for-administrators-guide","tag-linux-commands-for-administrators-reference","tag-linux-commands-for-administrators-tutorials","tag-linux-commands-guide","tag-linux-commands-reference","tag-linux-commands-tutorials"],"_links":{"self":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/358","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/comments?post=358"}],"version-history":[{"count":13,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/358\/revisions"}],"predecessor-version":[{"id":48665,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/358\/revisions\/48665"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/media\/3667"}],"wp:attachment":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/media?parent=358"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/categories?post=358"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/tags?post=358"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}