1. 1 Intro to Linux - getting around HPC systems Himanshu Chhetri

2. March 12, 2007 2 Introduction to Linux In 1990, Linus Trovalds, a Finnish Computer Science student developed Linux. He created the kernel but most of the supporting utilities was made by the GNU project of the Free Software Foundation. He was inspired by Minix, a classroom teaching tool which closely resembled the Unix OS. Linux is the result of the combined effort of many developers worldwide.

3. March 12, 2007 3 HPCI Clusters HPCI maintains two clusters based on Linux distributions: 1.AZUL azul.hpci.latech.edu (head node) 138.47.102.117 2.ITANIUM itanium.hpci.latech.edu (head node) 138.47.102.161

4. March 12, 2007 4 Connecting to HPCI Cluster From Windows 9x / 2003 Server / 2000 / XP / Vista: PuTTY is a free software SSH, Telnet, rlogin, and raw TCP client :

5. March 12, 2007 5 Connecting to HPCI Cluster From Linux/ Mac Os: Open the terminal and use the command line based ssh client:

6. March 12, 2007 6 Accessing user files remotely: From Windows 9x / 2003 Server / 2000 / XP / Vista: WinSCP is an open source free SFTP client for Windows using SSH.

7. March 12, 2007 7 Accessing user files remotely: From Linux/ Mac Os: Open the terminal and use the command line based scp client:

8. March 12, 2007 8 Filesystem You are automatically placed in your home directory after logging in. i.e. /home/user_name

9. March 12, 2007 9 Directories Listing files/directories: $ls Creating new directory and changing to it: $mkdir dir_name $cd dir_name Removing directory and all the files/subdirectories: $rm -rf dir_name

10. March 12, 2007 10 Working with permissions Display the permissions of current directory content: $ls -la Safely changing permissions to allow read,write and execution of file: $chmod 700 name_of_file Change permissions recursively: $chmod -R dir_name

11. March 12, 2007 11 File archiving : tar tar can save multiple files in a single file or do the vice versa Archiving a directory recursively: $ tar cvf name_of_archive.tar directory_name/ Extracting a tar archive contents: $tar xvf name_of_archive.tar

12. March 12, 2007 12 File Compression : gzip gzip is frequently used together with tar to archive and compress files: $gzip name_of_archive.tar name_of_archive.tar.gz is the resultant file Uncompressing “.tar.gz” files: $tar xzvf name_of_archive.tar.gz gunzip command uncompresses “.gz” files.

13. March 12, 2007 13 Text Editors: The systems have different kinds of text editors for editing source code,configuration files or plain text: vim : improved version of vi. Widely used. nano : enhanced version of pico editor. emacs : advanced text editor that offers additional features like sending/receiving emails and lisp interpreter ed : It is a simple line-oriented text editor

14. March 12, 2007 14 Managing processes : ps report a snapshot of all the current processes: $ps -ef| more show processes only run by certain user. Eg: show all processes being run by user hch018

15. March 12, 2007 15 Managing processes : top top command displays real time view of running processes and other related information: $top -u user_name

16. March 12, 2007 16 Managing processes : kill kill command terminates a process Process need to terminated in situations like if it cannot terminate normally. Eg : $kill -9 PID

17. March 12, 2007 17 User security : password passwd command can be used to change the user's password: Compromise of a user account can be prevented to a great extent with a strong password.

18. March 12, 2007 18 User Security : permissions chmod can be used to prevent other users from accessing files/directories owned by a rightful user. In above example chmod recursively gives appropriate permission only to user : hch018

19. March 12, 2007 19 User security : file integrity md5sum command generates a unique 128 bit checksum for a file. This is useful in verifying file integrity. Many open source projects provide md5 checksum for their packages.

20. March 12, 2007 20 Help/Documentation : man man command displays the manual page for a particular command/utility. Eg:

21. March 12, 2007 21 Network utilities : ping ping is a useful utility to check network connectivity.

22. March 12, 2007 22 Available compilers: gcc (GNU C Compiler): This is used to compile C programs g++(GNU C++ Compiler): This is used to compile C++ programs as / ld These are used to assemble and link assembly programs.

23. March 12, 2007 23 Available Interpreters / Scripting: python Compiler for the high level programming language. perl Compiler for the dynamic,interpreted high level language. gawk Compiler for awk : designed to process text data.

24. March 12, 2007 24 Resources : Official HPCI website: http://hpci.latech.edu Official HPCI mailing list: http://hpci.latech.edu/mailman/listinfo/hpc_users Alphabetical Directory of Linux Commands http://www.linuxdevcenter.com/linux/cmd/

25. March 12, 2007 25 Downloads: Putty http://www.chiark.greenend.org.uk/~sgtatham/putty/ Winscp http://winscp.net/eng/download.php Linux FAQs, Guides and HOWTOs http://tldp.org/

26. March 12, 2007 26 END Demo Of HPCI website and account request