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POS/420. Introduction to Unix. Philip Robbins – March 19, 2013 (Week 2) University of Phoenix Mililani Campus. Agenda: Week 2. Quiz #1 Due (Review & Grade) Week 2 File Structure Basic Terminal Commands Permissions In Class Lab (Assignment) #1 Due Today Take Quiz #2.

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pos 420


Introduction to Unix

Philip Robbins – March 19, 2013 (Week 2)

University of Phoenix Mililani Campus

agenda week 2
Agenda: Week 2
  • Quiz #1 Due (Review & Grade)
  • Week 2
    • File Structure
    • Basic Terminal Commands
    • Permissions
  • In Class Lab (Assignment) #1 Due Today
  • Take Quiz #2
review week 1 list of commands
Review Week 1 List of Commands
  • man – manual pages
  • ls– list directory contents
  • pwd– print working directory
  • passwd– change password
  • sudo– execute command as superuser
  • su– login as superuser
  • shutdown – shutdown

File Structure: Binaries

  • What’s the difference between:
    • /bin
    • /sbin
    • /usr/bin
    • /usr/sbin

File Structure: Binaries

  • What’s the difference between: /bin & /usr/bin
  • When UNIX was first written, /bin and /usr/bin physically resided on two different disks: /bin being on a smaller faster (more expensive) disk, and /usr/bin on a bigger slower disk.


  • Essential User Command Binaries
  • Contain commands used by both system administrators and users.
  • There must be no subdirectories in /bin.


  • Static files of the boot loader
  • Contains everything for the boot process (at boot time).
  • Does not include boot configuration files not needed at boot time.
  • Stores data that is used before the kernel begins executing.
  • OS Kernel is stored in either / or /boot.


  • Device Files
  • Location of special or devices files.


  • Host-specific system configuration
  • Contains configuration files.
  • Must be Static and cannot be an executable binary.
  • Required in /etc: opt, X11, sgml, xml


  • Data for services provided by this system.
  • - Contains site-specific data which is served by this system.
  • - Naming methodology not specified.
  • e.g. /srv/ftp, /srv/pos420/www
  • Data that is of interest to a specific user should go into that users home directory.


  • Temporary Files
  • Must be made available for programs that require the use of temporary files.
  • Recommend that /tmp files be deleted upon system reboot.


  • User Hierarchy
  • Second major section of the file system.
  • Used for shareable, read-only data.
  • Required directories:
  • bin - essential command binaries
  • sbin - essential system binaries
  • include - header files used by C programs
  • lib - object files, binaries, libraries
  • local - put apps you build yourself here
  • share - shared (Static)


  • What’s the difference between: /usr & /usr/local


    • Directory for System Manual Pages
  • man1:
  • User programs Manual pages that describe publicly accessible commands are contained in this chapter. Most program documentation that a user will need to use is located here.
  • man2:
  • System calls. This section describes all of the system calls (requests for the kernel to perform operations).
  • man3:
  • Library functions and subroutines. Section 3 describes program library routines that are not direct calls to kernel services. This and section 2 are only really of interest to programmers.
  • man4:
  • Special files. Section 4 describes the special files, related driver functions, and networking support available in the system. Typically, this includes the device files found in /dev and the kernel interface to networking protocol support.


    • Directory for System Manual Pages
  • man5:
  • File formats. The formats for many data files are documented in the section 5.
  • This includes various include files, program output files, and system files.
  • man6:
  • Games. This chapter documents games, demos, and generally trivial programs. Different people have various notions about how essential this is.
  • man7:
  • Miscellaneous. Manual pages that are difficult to classify are designated as being section 7. The troff and other text processing macro packages are found here.
  • man8:
  • System administration. Programs used by system administrators for system operation and maintenance are documented here. Some of these programs are also occasionally useful for normal users.


  • Manual Section Summary



Games. This chapter documents games, demos, and generally trivial programs. Different people have various notions about how essential this is.



  • Variable Hierarchy
  • Contains variable data files.
  • Spool files & directories, logging data, temporary files (for system reboots).
  • Not Shareable.
  • e.g. /var/log, /var/mail, /var/cache, /var/crash (dump files)
  • Can be placed in /usr/var. (If separate partition for /var is not possible).


  • Use the “more” command to view files.
  • man more for more information
  • view syslog
  • view kern.log
  • Also use the “head” and “tail” command to view files.
  • man head & tail for more information
  • know how to head & tail –n lines of a file


  • Kernel and process information virtual file system
  • Used for handling process and system information
  • Kernel and memory information
fhs compliant system
FHS Compliant System
  • Rationale:
    • Not all files can be shared
    • Static and Variable files should be segregated
    • Static files can be stored on read-only media
    • Different backup schedules
sudo fdisk l
sudo fdisk -l
  • Use fdisk to list all partitions (as root)
virtual terminals tty
Virtual Terminals (TTY)
  • Six tty (1 – 6)
    • Hold Ctrl + Alt, press F1 (for tty1)
    • F2 (for tty2) … F6 (for tty6)
    • Hold Ctrl + Alt, press F7 (to return to GUI)
    • Press and hold Ctrl + Alt to switch between VM and GUI
  • What is an OS shell?
  • Types
    • ksh, tcsh, csh, sh, bash
  • What shell are you running?
    • echo $SHELL
directory notation
Directory Notation
  • /
    • Represents a directory
  • /.
    • Represents current directory
  • /..
    • Represents the parent directory
  • /~
    • Represents a user’s home directory
file permissions1
File Permissions
  • Octal (numerical) Representation
run levels
Run Levels
  • runlevel
    • Previous runlevel, current runlevel
  • init
    • Change between run levels (process id 1)
  • telinit
    • Change system run level (user process)
  • Let’s take a break… RETURN @ 800PM
assignment 1
Assignment #1
  • 30 Questions
  • Use PrintScreen (PrtSc)
  • Work in groups (optional)
  • Submit individual assignments!
  • Post to OLS. -- use pdf format.
  • Due before you leave class tonight.
quiz week 2
Quiz: Week 2
  • 10-15 minutes