Orientation for fresh VDTT Students
Introduction to UNIX
July 28, 2001
Anup Gangwar
Embedded Systems Group
IIT Delhi
Overview
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Prerequisites and goals of this course
Differences between UNIX and Windows
Overview of unices
Basic UNIX commands and utilities
Lunch Break
File editors in UNIX
Programming and Shell Scripting
Document formatting using UNIX
References and further study
Thank You
Embedded Systems Group
IIT Delhi
Prerequisites and Goals
• What you should know
– Basic familiarity with computers
– Working Knowledge of atleast one operating system
– A will to learn
• What you will know
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This is not a complete UNIX tutorial
Don’t try to learn the whole UNIX in one day
How to do the most common set of tasks with UNIX
Self-Help is the best help
Pointers for further information
Embedded Systems Group
IIT Delhi
Differences: UNIX and Windows
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The UNIX and Windows philosophies
Client-Server model of Computation
Multi-User and Multi-Tasking. Login?
Concept of the Kernel and User Shell
Concept of file ownership and groups
GUI on UNIX and X windows
Tips:
– UNIX is the most used OS in scientific and industrial community
– Instead of avoiding UNIX take it heads on
– Learning UNIX now will help you save precious time later on
Embedded Systems Group
IIT Delhi
Overview of Unices-1
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The ?original? UNIX
The AT&T SVR and BSD
Others: HP-UX, Solaris, Linux, AIX, IRIX etc.
Why are there so many unices? Vendor Wars!
How do I understand all of them? POSIX!
Tips:
– Learn the common set of commands for all the unices
– Linux utilities will contain enhancements not found in others
– Try to clear trivial doubts like command syntax yourself
Embedded Systems Group
IIT Delhi
Overview of Unices-2
• HP-UX
– Processors: HP PA-RISC and Intel Itanium
– Vendors: HP
– Markets: High End Servers and Workstations
• Solaris/SunOS
– Processors: Sun Ultra Sparc
– Vendors: Sun Microsystems
– Markets: All ranges of Servers and Workstations
Embedded Systems Group
IIT Delhi
Overview of Unices-3
• Linux/GNU Systems
– Processors: Intel 386 and up, Sun Ultra Sparc, IBM
PowerPC etc.
– Vendors: Free/GNU GPL
– Markets: Low End Servers and Workstations
• AIX (Advanced UNIX)
– Processors: IBM Power PC
– Vendors: IBM
– Markets: All ranges of Servers and Workstations
Embedded Systems Group
IIT Delhi
Overview of Unices-4
• IRIX
– Processors: MIPS
– Vendors: SGI (Silicon Graphics International)
– Markets: High End Graphics Servers and Workstations
• Others
– BeOS, FreeBSD etc.
– RTOS’s: PSoS, QNX, RTEMS, ?RTLinux? etc.
Embedded Systems Group
IIT Delhi
What we have
• Philips VLSI Design Lab
– HP Server running HP-UX
– Sun Workstation
– Linux Workstations
• VDTT Lab
– Linux Workstations
– Windows NT Workstations
• New VLSI Lab
– Sun Workstations
– Windows NT Workstations
Embedded Systems Group
IIT Delhi
Basic UNIX Commands and Utilities-1
• Files and Directories
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File Types: Windows and UNIX
File and Directory creation (Editors, mkdir, ln etc.)
Listing contents of a directory (ls)
File and Directory deletion (rmdir, rm etc.)
File and Directory permissions (chmod)
File and Directory ownership (chown, chgrp)
Organizing your work in directories (mv)
• Tips:
– UNIX doesn’t have a recycle bin!
– Try not to make the mistake of rm -rf * command
Embedded Systems Group
IIT Delhi
Basic UNIX Commands and Utilities-2
• Managing your account
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What is meant by managing your account?
Concept of setup files
Why are there so many different Shells?
Environment variables
.bashrc and .cshrc files
Customizing your environment with .bashrc and .cshrc files
Example: The TERM environment variable and stty
Tips:
• Try an environment variable on command-line first
• Always set the PATH variable properly
Embedded Systems Group
IIT Delhi
Basic UNIX Commands and Utilities-3
• Remote process execution
– Why do we need remote process execution?
– Telnet and rlogin
– Remote execution of graphics programs
• X-Security, granting permissions and colormap
• The DISPLAY environment variable
– dot-rhosts (.rhosts), xon
– Moving files between computers: FTP (?anonymous? FTP login)
– Tips:
• Graphics performance suffers in remote graphics execution
• xhost+ is the worst thing to do!
• Ncftp is a better ftp client than the vanilla default UNIX ftp
Embedded Systems Group
IIT Delhi
Basic UNIX Commands and Utilities-4
• Taking printouts
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Concept of network and local printers
Printer languages: Postscript and PCL
GhostView and Acroread programs
Spooling, Deleting and Checking a printer job
Duplex printing and mpage
• Taking backups
– Tarring, zipping, gzipping and compressing
– Comparison with winzip and common filename extensions
• Tips:
– Do not issue the command tar -cvf <file-name> *
– Acroread just might be a better program to open pdf files
Embedded Systems Group
IIT Delhi
Basic UNIX Commands and Utilities-5
• Miscellaneous stuff
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Forcing a process in background (&, fg, bg)
Setting aliases
Online manual pages, man
Concept of NIS and NFS
Changing password, passwd (?yppasswd?)
Searching for patterns, grep and regular expressions
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Working with files with special characters in names
The file utility
finger, who and rwho
ps and kill
Mail and mail clients, netscape, pine, emacs and mail
startx, .Xclients and .xinitrc files
• Tips:
– Instead of asking someone try man -k
– It is a good practice to stick to one shell (csh is available on all)
Embedded Systems Group
IIT Delhi
Lunch Break
Embedded Systems Group
IIT Delhi
Editors in UNIX-1
• What all is available, Vi, Emacs, Pico, Joe?, Nedit?
• Vi: The king of all editors? Tutorial?
– Why learn vi?
– Getting in and out?
– Basic keys for editing
• Moving around, deleting, joining lines
• Repeating commands
• Search and replace
– Tips:
• Vim is not Vi
• Learn the keypad scroll key combinations instead of arrow keys
• Vi is fast, try to make the best use of its capabilities
Embedded Systems Group
IIT Delhi
Editors in UNIX-2
• Emacs: Much more than an editor?
– Why learn Emacs? History, Tutorial
– Getting in and out?
– Basic keys for editing
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Moving around, deleting a line
Search and replace
Formatted text, postscript spooling
mail in emacs
– Syntax highlighting and templates
– Tips:
• Emacs recognizes 20+ languages out of the box
• Emacs is slow
• Emacs is not available by default on all unices
Embedded Systems Group
IIT Delhi
Editors in UNIX-3
• Pico: Is there really a need?
– Pico and Pine
– Editor Keys
• Joe?, Nedit?
– Keys similar to Norton Editor
– Nedit has some features similar to Emacs
• Tips:
– Don’t fall for Pico or Nedit
– Learn Vi and Emacs if you really want to get into UNIX
– In the end it is a matter of choice
Embedded Systems Group
IIT Delhi
Programming on UNIX-1
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Is programming on UNIX tough? What all is available?
Concept of IDE and differences with TurboC++
Compilers, Linkers, Debuggers and front-ends
Managing big projects: make and comparison with TC
project file
Example of a simple makefile
GUI development on UNIX
Java
Tips:
– UNIX is a programmers paradise
Embedded Systems Group
IIT Delhi
Programming on UNIX-2
• Gcc, The GNU C/C++ compiler
– Simplest possible way to use: gcc <file-name>
– Common options
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output filename: -o
compile only: -c
Warnings: -Wall
optimizations: -O{1,2,3,4}
Debug: -g
Linking: -l<library-name>
– Tips:
• Not every UNIX systems will have gcc
• Turning on optimization makes the compilation slow
• Debugging and optimizing donot go together
Embedded Systems Group
IIT Delhi
Programming on UNIX-3
• Ld, The Linker
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What exactly are libraries?
Shared and static libraries
Is there a need to call Ld explicitly?
Passing options to Ld from gcc
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The -l option
The -L option
The LD_LIBRARY_PATH environment variable
The LD_RUN_PATH environment variable
– Tips:
• Always check the Ld on the system, HP-UX doesn’t use GNU Ld
• Environment variables are different with non GNU Ld
Embedded Systems Group
IIT Delhi
Programming on UNIX-4
• Gdb, The GNU C/C++ debugger
– Why is a debugger needed?
– gdb and ?core? File
– Common commands
• list
• run, break, resume
• backtrace and where
– Tips:
• Using gdb directly might be tedious
• Try the various front-ends to gdb: emacs, xxgdb, mxgdb etc.
• Not every system will have gdb, you just might have to use ?dbx?
Embedded Systems Group
IIT Delhi
Programming on UNIX-5
• Gmake or GNU make
• What is the need for a Makefile?
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Dependencies
Targets in a makefile
Patterns in makefile
Automatic variables in a makefile
Pattern substitution
Common target names: all, clean, docs
• Tips:
– Never forget the TAB
– Make is language independent!
Embedded Systems Group
IIT Delhi
Programming on UNIX-6
• Example of a makefile
CC=gcc
COPTS= -g -Wall
TARGET=run.x
SRCS=hello.c junk.c
OBJS=$(SRCS:.c=.o)
all:$(OBJS)
$(CC) $(COPTS) $(OBJS) -o $(TARGET)
clean:
rm -f $(OBJS) core
%.o:%.c
$(CC) $(COPTS) -c $<
Embedded Systems Group
IIT Delhi
Programming on UNIX-7
• GUI in UNIX?
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Differences with TurboC++
Vanilla X windows programming, why not?
TCL/Tk
Widget libraries
• Motif
• GTK
• QT, etc.
– Tips:
• Always provide a command line interface to your programs
• Using a GUI is slow
Embedded Systems Group
IIT Delhi
Programming on UNIX-8
• Java
– What is really different with the windows version?
– Is Jfc, Java2D, Java3D available?
– IDE’s for Java over UNIX?
• Tips:
– Don’t try to use a %.class dependency with make
– If you run Java from a server, graphics would be slow
Embedded Systems Group
IIT Delhi
Introduction to Shell Programming-1
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What is the need for shell programming?
Bourne shell (sh, ksh, zsh and bash)
c shell (csh, tcsh)
Examples of shell programming
– Moving all a.{i}.txt files to a.{i+1}.txt
– Cleaning up your directory at the end of a day
• Tips:
– Perl just might be a better option
– Don’t forget ?sed? and ?awk?
Embedded Systems Group
IIT Delhi
Introduction to Shell Programming-2
• Moving files script
#!/bin/sh -f
FILE_LIST=`ls | grep "\.[0-9]\." `
for CURR_FILE in $FILE_LIST; do
FIRST_NM=`echo $CURR_FILE | cut -d'.' -f1`
NUM=`echo $CURR_FILE | cut -d'.' -f2 `
SECOND_NM=`echo $CURR_FILE | cut -d'.' -f3`
NUM_PLUS=`expr $NUM + 1 `
mv -i $CURR_FILE $FIRST_NM.$NUM_PLUS.$SECOND_NM
done
Embedded Systems Group
IIT Delhi
Introduction to Shell Programming-3
• Cleanup directory script
#!/bin/csh -f
# Assume that ps, pdf etc. directories are present
set FILE_LIST=`ls`
foreach CURR_FILE ( $FILE_LIST )
set TST=`echo $CURR_FILE | grep \.pdf\$ `
if( $TST != "" ) then
mv $CURR_FILE pdf
endif
set TST=`echo $CURR_FILE | grep \.ps\$ `
if( $TST != "" ) then
mv $CURR_FILE ps
endif
end
Embedded Systems Group
IIT Delhi
Text formatting using UNIX-1
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What is the need for text formatting?
WYSWYG or NOT?
LaTeX & Emacs PS renderer
LaTeX WYSWYG front-end Lyx
Other text formatters: ?troff?
How to make Presentations? Slides?
Tips:
– PowerPoint is still the best software for making presentations
– It is easy to convert PowerPoint slides to html
Embedded Systems Group
IIT Delhi
Text formatting using UNIX-2
• LaTeX
– origin: LaTeX and TeX
– usage
– LaTeX tutorials and manuals
• A not so short introduction to LaTeX
• The LaTeX manual
• LaTeX by Lesslie Lamport
• Lyx a WYSWIG interface to LaTeX
• Emacs ps-renderer and troff
• Tips:
– For small formatted text Emacs is still the best
Embedded Systems Group
IIT Delhi
Before wrapping up
Any questions/doubts which you would like to clarify?
Embedded Systems Group
IIT Delhi
Wrapping up
• Self help is the best help!
– The UNIX man pages. ?Manual sections?
– Using man, whatis etc.
– Experiment. You can never kill the system.
• Links
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http://www.gnu.org, for GNU tools and manuals
http://sunsite.unc.edu, world’s largest collection of free software
http://upavan.cse.iitd.ernet.in, Philips Lab. internal page
http://poorvi.cse.iitd.ernet.in/local, Intel cluster archives
• Books
– The UNIX programming environment, Kernighan & Pike
Embedded Systems Group
IIT Delhi
Thank You
Embedded Systems Group
IIT Delhi