VIEWS: 5 PAGES: 29 POSTED ON: 8/22/2011
Linux Workshop Session 1 Khadka, Santosh and Panthi, Sanjeeb Computer Science Department Lamar University What is covered? Working with files Working with directories Some basic commands Process related commands Working with vi editor Brief Introduction to Nano Editor Login! Galaxy Account can be used to access all the Linux machines in the lab 208, both locally and remotely • To access locally, go to the any machines in 208 and use your username and password to login. • To access remotely, use any secure shell (ssh) software. Example puTTY . • Open a terminal by right clicking on your desktop. • Type pwd -> shows the current working directory. You are in your home directory. Tools Required for Remote Access • ssh client - Example: putty for Windows platform • sftp client - Example: WinScp for Windows platform • remote sftp compatible editor - Example: jEdit for platform that supports java Working with files • To list all the files and/or folders in a current directory by default. ls [option]… [file]… • Options: • -a: to list all files • -l: to list in long format showing file attributes and permission • --author : gives the author name of the files. Better use with the combination of –l. • File: Default is current working directory. Working with files • vi <filename> -opens a file to edit if exist, otherwise creates new file to edit • ls - lists contents in current directory • ls /etc - lists contents in directory /etc • ls -a - this will list all file including those beginning with the'.' that would normally be hidden from view. • Output redirection - Copies the output to some other file. Example: ls –l > filename (overwritten) ls –l >> filename (appended) Working with files • ls -l - this gives a long listing showing file attributes and file permissions. drwxrwxr-x 6 santoshk santoshk 4096 Sep 14 11:39 test -rw-rw-r-- 1 santoshk santoshk 140 Nov 17 09:08 test1.c • cat <filename> - displays the content of the file - example: cat filename - cat –n filename (-n option for giving the line number)d • cp <sourcefile> <destinationfile> - copy the content of the file - example: cp sourcefile.txt destnationfile.txt (source file is not deleted/modified) Working with files • script - to make script file - records everything printed on your screen. The record is recorded to the filename specified. - starts scripting, once done, type in <ctrl>+d to end scripting Example: script filename - makes a script file with the given filename script -a filename - append the session record to filename, rather than overwrite it • mv <sourcefile> <destinationfile> - example: mv sourcefile.txt destiantionfile.txt (the sourcefile file is deleted) Working with files • tar - create archives and add or extract files • tar –cvf output.tar inputfile Example: tar –cvf aos.tar AOS • restore a tar file - tar -xvf inputfile.tar - .tar file is not compressed by itself. It just bundles the list of files in one folder. - add -z option to create a compressed tar file Example: tar -cvzf file.tar.gz Working with files .gzip – compress the files Example gzip <filename> .gunzip –decompress the file Example gunzip <filename.gz> Working with files • wc - counts the number of lines,words and bytes in the file - example: wc –l filename • head - outputs the first part of the file - prints the first 10 lines by default - example: head filename head -n count filename • tail - outputs the last part of the file. - example: tail mylist.cpp Working with files • lpr - print command - command: lpr -p printername filename Example: lpr -p lab208Printer -#2 file1.txt file2.txt (this will print two copies of file1.txt and file2.txt) Note: This is not available at present. Working with directories • cd - changes the directory - example: cd <foldername> • mkdir - creates a directory under the current working directory. - example: mkdir <foldername> • rmdir - remove files - example: rmdir <directoryname> (for empty directory) rmdir –rf directoryname (recursive deletion with force) Working with files contd.. • Absolute path: start with / (root) to go specific directory regardless of where you are now. • Relative path : start with the current directory to go specific directory. • Example: • If, pwd: /home/myfolder then to go /home/myfolder/c++ • Absolute path : cd /home/myfolder/c++ • Relative path : cd c++ A few basic commands • man - help manual - example: man keyword - press <Space bar> to view the next page - press <return> to view next line - type“q”exit • date - display or change the date - example: date --date 2„=daysago‟ date --set=“2009-9-4 11:59” date '+DATE: %m/%d/%y%n TIME:%H:%M:%S' DATE: 02/08/01 TIME:16:44:55 A few basic commands • chmod - used to change the access permission - used to set file permissions to owner, group, and other -rw-rw-r-- 1 santoshk santoshk 140 Nov 17 09:08 test1.c - r = 4, w = 2, x = 1 - example: chmod 444 mylist • clear - clear the screen • grep - search the file for the specific text - example: grep string filname A few basic commands • hostname - displays or set the system name - example: hostname [name] - with no arguments prints the current host name. - with arguments sets the current host name to the specified string. • more - display output one screen at a time - related command: less • quota - display disk usage and limits - related command: du, df du –estimate the file space uses df – disk space uses (amount of disk space available) Process related commands • ps - gives information about the running processes - example: ps -ef ps -fu username • kill - sends a signal to a process to kill (ends the running process) - example: kill -9 pid • exit - exit from the shell. If there are suspended jobs one cannot exit from the shell , so kill the processes using the kill command. Brief Introduction to vi Editor • vi filename • esc - to enter vi command mode • h: moves the cursor one character left (l right) • j :moves the cursor one character down (k up) • u :undo the last changes in the file • x :deletes the character under the cursor • d^: deletes all the characters from current cursor to beginning of the line • d$ :deletes all the characters from current cursor to end of the line • dw: deletes one word from the cursor. Brief Introduction to vi Editor contd.. • Insert text Enter input mode and: i a - insert text before ('i') or after ('a') the current character I A - insert text at beginning ('I') or end ('A') of current line o O - open new blank line after ('o') or before ('O') current line r R - replaceone(„r‟)ormorecharacter„(R‟)byoverwriting Brief Introduction to vi Editor • Exiting and Saving - Press esc and type :q to quit :wq or ZZ to save and quit :q! to quit without saving (!= Forcefully) :w to save the file :w filename to save current file under name filename • Copy and Paste text nyy or nY - 'copies' n number of line pP - insert the contents of the paste buffer [ after / before ] the current line/character. Brief Introduction to vi Editor • Delete text x X - Delete current ('x') or previous ('X') character dw - Delete the current word dd - Delete the current line D - Delete the rest of the line 5dd - Delete the next five lines 37Gdd - Delete line 37 J - Join lines • Undo u - Undo most recent change to the file Brief Introduction to vi Editor • Global Searching and replace: /text - Search forward for some <text> ?text - Search backward for some <text> n - Repeat the previous search for the 'next' occurrence N - Repeat the previous search but in the opposite direction ' ' (two single quotes) - Go back to where you where previously :1,$s/oldtext/newtext/g - global substitutions Brief Introduction to vi Editor • Other popular commands ^ - go to start of line $ - go to end of line :1 - goes to top of file :5 - goes to fifth line of file :$ - goes to bottom of file :set nu - will number all your lines :set nonu - turn off line numbering Ctrl-g - show line number of current line Brief Introduction to Nano Editor • To edit a file called filename, type nano filename. • cntrl g - (^G) with display a Help file with a bunch of information about using nano. • cntrl o - (^O) or (f3) will write or save the file • cntrl x - (^X) will exit the program and return you to the prompt • cntrl d - (^D) delete character currently under the cursor • cntrl k - (^K) delete entire line • cntrl u - (^U) paste text • ^\ - search for (and replace) a string of characters • BackSpace delete character currently in front of the cursor Compiling files in linux • C++ file g++ [options] source_file –o outputfile g++ myfile.cpp g++ -Wall myfile.cpp -o outputfile • C file gcc [options] source_file –o outputfile gcc myfile.c • java file javac Myfile.java java Myfile Debuggin c/c++ file • gdb outputfile • To set the break • (gdb) break filename:line number • (gdb) functionname • To remove the break • (gdb) clear function /line number • To run • (gdb) r • (gdb) step (each step) • (gdb) next [count] // how many line Debuggin c/c++ file • To watch the variables • (gdb) watch variablename • (gdb) watch expression • To quit • (gdb) q Thank You !!!
"Basic Commands in Linux"