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This comprehensive guide covers the basics of UNIX command line, including file and directory manipulation, process management, killing processes, working with environmental variables, using pipes, and redirection techniques.
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Introduction to Computer Organization & Systems COMP 21000 Spring 2018 Topics: • UNIX command line • C - everything UNIX/Linux Command Line
Unix • Passwords • Changing • passwd • whoami • finger and the .plan file • Help • about a command • man cmdName • apropos cmdName • which cmdName ;gives path to the application
Unix • Directories • Seeing, manuvering, creating • cd /path/to/new/directory • pwd • ls [-a –l] • mkdir dirName • rmdir dirName • rm –r dirName • pushd . • popd
Unix • Files • Moving, deleting • cp src dest • rm fileName • Viewing • more fileName • cat fileName1 fileName2 • Permissions • ls –l • chmod 777 fileName
Unix • Processes • What’s running? • ps ;only your processes • ps –a ;all processes PID TTY TIME CMD 33129 ttys000 0:00.02 -bash 33178 ttys000 0:00.00 man builtin 33186 ttys000 0:00.00 /usr/bin/less -is 33131 ttys001 0:00.01 -bash 33130 ttys002 0:00.02 –bash
Kill • kill command is used to stop a running process • A user can kill all his process. • A user can not kill another user’s process. • A user can not kill processes System is using. • A root user* can kill System-level-process and the process of any user. * the root is the administrator
Kill • kill -9 pid;kill process pid • other ways to kill • kill by name • pkilla.out;kill all processes named a.out • kill on the command line • ^c ;hold down control key and press the c key ;kills currently running process
More Unix • Shells • Environmental variables (capitalization counts!) • Echo $ENV • $PATH • .bashrc and.bash_profile files • alias • changing $PATH • using source to act on changes to the file • Pipes • using the | operator to connect programs
More Unix • Redirection • using >and>> to redirect stdout to a file • > to overwrite • >> to append • using &> to redirect stdout and stderr to a file gcc –g -o ex1 ex1.c > err.txt &> err.txt • using < to redirect stdin from file • History • the ! operator