Physics Linux System
User's Guide

A short introduction to the most commonly used Unix (Linux) commands. For more info, read a book¹or read the info pages.

Welcome to McGill.

Before we start, let's talk about a few basic rules you must respect.

• The computer on your desktop is not yours. It belongs to the Department. It is loaned to you so that you can do physics. Please do not abuse this privilege.
• If any serious problem occurs, do not try to deal with it yourself. Contact the operators at [email protected] (Paul and Juan).
• Never turn off, reset or reboot your computer. Our computers are shared resources. Others may be running jobs on your desktop. In case of emergency, contact the system operators.

• The above principles also apply to the printers. In addition, our printers need special transparency films. Never use ordinary transparency films in the printers. It will jam. Ask the system operators for the transparency films.

• Never unplug anything or plug in anything without permission.
• If you bring your laptop, you must ask your supervisor to get you a new ethernet socket to connect to the Net. Never unplug the ethernet connection from your desktop. In addition, if your laptop is running Windows, it is your responsibility to make sure that it is properly firewalled and updated constantly with the latest Microsoft patches.

• You are not allowed to set up switches, hubs or your own wireless networks.

• Do not abuse your disk space. Keep only the necessary files on your disk. Personal items should be promptly transferred to your own computer.

Quick Reference

Changing Password

• yppasswd : Changes your password.

Information

• info : To find out about a command.

  (ex) info lpr

  To search info pages for a keyword

  info --apropos=keyword

• man : To read a manual page about a command.

  (ex) man lpr

Directory related commands

• ls : Lists files and subdirectories in the present directory.

• mkdir : To make a directory.

  (ex) mkdir sub_dir

• rmdir : To remove an empty directory.

  (ex) rmdir sub_dir

• cd : ``change directory"

  (ex) cd sub_dir

• pwd : ``print working directory''

File & Directory related commands

• cp : To copy a file or a directory.

  (ex) cp original copy

  (ex) cp -r original_dir copy_dir (Be careful with this!)

• mv : To move a file or a directory.

  (ex) mv old_name new_name

• rm : To remove a file.

  (ex) rm file

• more or less : To read a file.

  (ex) less unix.txt

• nedit, kdedit, vi, emacs : To edit a file.

  (ex) nedit unix.txt

• tar : To collect a number of files and directories in one big file.

  To make : tar cvf all_files.tar file1 file2 files*

  To un-tar : tar xvf all_files.tar

• gzip or bzip2 : To compress a big file.

  (ex) gzip all.tar

• gunzip or bunzip2 : To decompress a zipped file.

  (ex) gunzip all.tar.gz

Compiling and running programs

• gcc or cc : C Compiler.

  (ex) gcc -o prog_name file.c files.*.c -lm

• g77 or f77 : Fortran 77 Compiler.

  (ex) g77 -o prog_name file.f files.*.f

• qsub : To submit to the batch que.

• <ctrl>c : To interrupt a running program.

• <ctrl>z : To suspend a running program.

• bg : To run the suspended job in the background.

• fg : To run the suspended job in the foreground or to bring a job in the background to the foreground.

• jobs : To list your jobs running in the background.

• ps -u : To list all of your processes

• kill : To kill a job or a process

L^ATEX, PostScript, PDF, Printing

• latex : To latex a L^ATEXfile.

  (ex) latex unix.tex

• xdvi : To preview a .dvi file on an X-terminal.

  (ex) xdvi unix.dvi

• dvips : To make a PostScript (ps) file from a dvi file to preview or to print.

  (ex) dvips unix.dvi -o unix.ps

• gv: To preview a ps file or a pdf file.

  (ex) gv unix.ps

• dvips -Ppdf : To make a pdf-ready ps file

  (ex) dvips -Ppdf unix.dvi -o unix.ps

• ps2pdf: To make a pdf file from a ps file.

  (ex) ps2pdf unix.ps

• acroread, xpdf, gv: To preview and print a pdf file.

  (ex) acroread unix.pdf

  (ex) xpdf unix.pdf

• lpr : To print a PostScript file or a text file.

  (ex) lpr unix.ps

• lpstat or lpq : To ask a printer how it is doing.

E-mail, WWW, Connecting

• pine : To read and send e-mails.
  • To read an email, just enter.
  • To `compose' a new email, press c.
  • To `reply', press r.
  • To `delete', press d.
  • To `save', press s.
  • To change levels, use <, >
  • To send files, use `attachment'.
  • To quit pine, press q.

• mail [email protected] < file : To send an ascii file without going through an e-mail program.

• mozilla & : To run the web-browser Mozilla in the background

• ~/WWW : Your McGill homepage location if you are with HEP/TNP/ASTRO.

• /WWW/user_name : Your McGill homepage location if you are with CMP/GANG.

• ssh [email protected] : To securely login to other computers. Also use this to connect from home.

• scp : To securely copy a file from one machine to another.

  (ex) scp file_1 [email protected]:file_2

  (ex) scp [email protected]:file_1 file_2

• sftp : To securely transfer files from one account another

• To get your mails from outside McGill: Log in using ssh and do pine.

  Or, configure your browser/outlook with IMAP with SSL and set the Incoming server to hepmailhost.physics.mcgill.ca (for HEP/TNP/ASTRO)
  or imap.physics.mcgill.ca (for CMP/GANG). SMTP is mx1.hep.physics.mcgill.ca port number 587.

Other useful commands and programs

• ypchsh : To switch your shell globally. Default is tcsh.
• chmod : To change the attribute of a file or a directory.

  Usage: chmod [ugoa][+-][rwx] file

• df : To check filesystem disk space usage

• du : To check your own disk space usage

• convert : To convert one graphics format to another.

  (ex) convert picture.eps picture.jpg

• display : To view a graphics file

  (ex) display picture.jpg

• nice : To be nice to other people using the same machine

  (ex) nice convert huge_picture.eps huge_picture.jpg

• < : Treat the lines in a file as keyboard inputs (STDIN: standard input).

  (ex) prog < input_dat

• > : To redirect the standard output (STDOUT) of a program to a file.

  (ex) prog < input_data > output_data

• >> : To append the output of a program to a file.

  (ex) prog < input_data >> output_data

• | : Pipe. To pass STDOUT as a file.

  (ex) grep verb unix.tex | less

• grep : To globally search for a regular expression and print the lines containing it.

  (ex) grep verb unix.tex