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Just Enough UNIX. UNIX Operating System. Generally operates from a command-line. After logging on, met with command-prompt: grid x : In labs, you will be using X-windows on X-terminals. UNIX commands. All UNIX commands are actually programs.

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Unix operating system
UNIX Operating System

  • Generally operates from a command-line.

  • After logging on, met with command-prompt:

    • gridx:

  • In labs, you will be using X-windows on X-terminals.


Unix commands
UNIX commands

  • All UNIX commands are actually programs.

  • You “run” a program by typing its name at the command prompt.

  • Generally, the output of a program goes to the screen and if the program requires any input, it gets it from the keyboard.

  • These are called:

    • stdout & stdin


File navigation and manipulation
File navigation and manipulation

  • UNIX uses a hierarchical file structure.

  • Very similar to Windows and Macintosh.

  • Directories not folders.

  • Move about with typed commands rather than mouse-clicks.


Just enough unix
ls

list

Displays the names of the files in the current directory.

Flags:

-a: shows all the files, including hidden ones

-F: puts a / after directories, an * after executables, and an @ after links

-l: displays a long listing of files


Just enough unix
pwd

print working directory

Displays the full path of the current directory you are in.

e.g.: /home/CS/cs153/801/skea1234/programs


Just enough unix
cd

  • change directory

  • Changes your working directory to whatever you specify.

    • cd [name of directory]

  • Without any directory (just cd) you will be taken to your home directory.

    • cd

  • With .. you will be taken to the parent of the working directory

    • cd ..


Just enough unix
cp

copy

Copies the contents of one file to another.

cp [file to copy] [new file name]

Copies a file from one directory to the working directory

cp [path of file to copy] .


Just enough unix
mv

move

Better name could be the rename command.

Changes the name of one file to another.

mv [old file name] [new file name]

Note that the [new file name] could be a directory, which will effectively move the file to the new directory keeping the original name.


Just enough unix
rm

remove

Deletes the specified file or files.

This is destructive!

They are gone!

They cannot be retrieved!!!

rm [file name]

Note: this does not generally work with directories.


Mkdir
mkdir

make directory

This creates a directory.

mkdir [new directory name]

Does not automatically change to the new directory after it is created.


Rmdir
rmdir

remove directory

This deletes a directory (as opposed to the rm command above).

The directory must be empty otherwise you will get an error.


Just enough unix
man

  • UNIX reference manual

  • Gives usage, options, examples for UNIX commands and applications

  • man [command name]

    • $: man pwd

    • $: man man

  • Option –k searches the manual pages by keyword

    • $: man –k “working directory”


Access privileges
Access privileges

  • All UNIX files have privileges associated with them.

  • These privileges determine who can access the file.

  • These privileges determine how people can access the file.


Viewing access privileges
Viewing access privileges

  • Use the ls -l command.

drwx------ 2 jimd 8192 Jul 12 12:26 nsmail/

-rw-r--r-- 1 jimd 945 Mar 15 16:01 old.cshrc

-rwxrwxrwx 1 jimd 168 Jan 13 1998 file.exe

-rw-rw-rw- 1 nobody 382 Nov 18 1998 old.profile

-rw------- 1 jimd 652 Jul 12 12:16 old.xsession

drwx------ 2 jimd 8192 Jun 23 13:21 thesis/

-rw-r--r-- 1 jimd 1186776 Jul 13 15:07 win32tutorial.ps


Types of file access rwx
Types of file access - rwx

  • Read — person can look at the contents of the file.

  • Write — person can change the file.

  • eXecute — person can execute the file (applies only to directories and program).


Types of users ugo
Types of users - ugo

  • User/owner -- the person who owns/created the file.

  • Group — UNIX allows for the creation of groups.

  • Others/world -- everyone else in the world that has access to that computer.


To change permissions
To change permissions

chmod — changes the access mode of a file.

Two methods exist

symbolic

absolute


Chmod absolute
chmod - absolute

  • Absolute - you specify a numeric equivalent for a set of permissions.

  • You specify all permissions at once.


Chmod absolute1
chmod - absolute

  • chmod [xxx] [file]

  • Where each x is some number from 0 - 7.

  • Each number specifies a level of privileges for a specific group.


Chmod absolute2
chmod - absolute

  • e.g.,

chmod 644 index.html

User permission

World permission

Group permission


Chmod absolute3
chmod - absolute

  • Permissions:

    • Read = 4

    • Write = 2

    • Execute = 1

  • Set permissions by adding the values of all the permissions you wish to set.


Chmod examples
chmod - examples

  • To give yourself read & write permission and no permission to anyone else:

    • chmod 600 foobar.txt

  • To give yourself read & write permission and everyone else read permission only:

    • chmod 644 index.html

  • To give yourself full access to a directory, and everyone else read & execute permission only:

    • chmod 755 images


Chmod symbolic
chmod - symbolic

  • symbolic - you specify only the changes to be made to the permissions

  • You specify changes for only one user-type.


Chmod symbolic1
chmod - symbolic

  • chmod [user-type + or – rwx]

  • Where + signifies adding permission and - signifies removing permission

  • rwx - include only the permissions to by updated.


Chmod symbolic2
chmod - symbolic

  • e.g.,

  • e.g.,

chmod g+rw index.html

User-type

Permissions changed

Change to be made


Just enough unix

chmod - examples

  • To add read & write permissions for yourself:

    • chmod u+rw foobar.txt

  • To remove write and execute permissions for everyone who is not user or group:

    • chmod o-wx images

  • To add write permissions for the group:

    • chmod g+w index.html