UNIX Overview

2 UNIX UNIX is a multi-user and multi-tasking operating system. Multi-tasking: Multiple processes can run concurrently. Multi-user: different users can read mails, copy files, and print all at once.

Basic Command Suite CommandMeaning lslist files and directories ls -alist all files and directories mkdirmake a directory cd directorychange to named directory cdchange to home-directory cd ~change to home-directory cd..change to parent directory pwddisplay the path of the current directory

Man Pages Manual pages are on-line manuals which give information about most commands –T–Tells you which options a particular command can take –H–How each option modifies the behavior of the command Type man command at the UNIX command line to read the manual for a command What does the wc (word count) command do? … Type % man wc Alternatively, % whatis wc –A–A one-line description of the command, but omits information about options, etc.

More Useful Commands CommandMeaning cp file1 file2copy file1 and call it file2 mv file1 file2move or rename file1 to file2 rm fileremove a file rmdir directoryremove a directory cat filedisplay a file less filedisplay a file a page at a time head filedisplay the first few lines of a file tail filedisplay the last few lines of a file grep 'keyword' filesearch a file for keywords wc file count number of lines/words/characters in file

CommandMeaning command > fileredirect standard output to a file command >> fileappend standard output to a file command < file redirect standard input from a file command1 | command2 pipe the output of command1 to the input of command2 cat file1 file2 > file0 concatenate file1 and file2 to file0 sortsort data wholist users currently logged in *match any number of characters ?match one character man command read the online manual page for a command whatis commandbrief description of a command apropos keyword match commands with keyword in their man pages

7 How to stop a process? Foreground processes can generally be stopped by pressing CONTROL C (^C). Background processes can be stopped using the kill command. Usage: kill SIGNAL kill -9 (-9 means no blocked) Or kill. If a foreground process is not stopping by ^C, you can open another session and use the kill command.

8 Text editors Different editors: emacs, pico, vi emacs pico vi linux-text-editors/

9 The simplest editor: pico or nano pico Full screen editor Help on the bottom of the screen nano is an extension to pico

10 Basic operations in pico Ctrl + v : to move page down Ctrl + y : to move page up Ctrl + o : to save the current buffer Ctrl + x : to exit with or without saving Ctrl + g : to get help Ctrl + r : to open a file Ctrl + w : to find a string in the current buffer Ctrl + c : to get the current position in the buffer

UNIX Tutorial Resources tutorial.html tutorial.html rial.html rial.html

Get Your Feet Wet Read man pages to learn other commands such as: – gzip, cat, zcat, diff, find, history, diff, more, less, source Learn about the Bash shell – Debugger – Debugging a multi-process program is difficult with a debugger such as gdb – It is recommended that you use lots of printf statements during development