Lesson Working with Unix

Working with Unix

Working With Unix

Unix Command Syntax

Unix Overview

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Unix Command Syntax
Each Unix command has a defined syntax:
• Abbreviated spelling
• Required elements
Most Unix commands have options:
• The long (-l) or all (-a) used by ls

Unix Command Syntax
There are 3 methods to research the
syntax of Unix commands too see a
complete list of requirements and options

• Use the man command and browse the
Man Help Pages
-> man <command> <enter>

Unix Overview

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Unix Command Syntax

• Type in the command name at the Unix
prompt and hit enter
-> <command> <enter>

• Use a Google search
-> Unix <command> command

Unix Command Syntax
• Use the man command

Unix Overview

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Unix Command Syntax
• type command at prompt

Unix Command Syntax
Use a Google search

Unix Overview

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Unix Command Syntax

Results of Google search

Working With Unix

Special Characters

Unix Overview

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Special Characters

In Unix, special characters such as input
or output redirection, regular expressions
(such as wildcards and delimiters), and
other special pattern-matching
characters have a special meaning.

Special Characters
Unix special characters might not work
in every Unix shell or might have
different options in different shells.
Simply try the special character and see
if it works in the current shell.

Unix Overview

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Special Characters
Special
Characters

Explanation

*

Matches any set of characters

?

Matches a single character

-

Often used to prefix a parameter

/

Directory marker and root directory

\

Line continuation or other escapes

.

The current directory

< or >

Redirect Input or Output

|

Pipe output

&

Run command in background

$

Prefix for environment variable

Special Characters
* Command – match all characters
• ls t*
-> list all files starting with letter t
? Command – match 1 character
• ls prog?.cob
-> list all 5-character prog .cob files

Unix Overview

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Special Characters
< Command – redirect input
• runproc < data_in
-> get input data from data_in not keyboard
> Command – redirect output
• runproc > data_out
-> print output to file data_out not monitor

Special Characters
| Command – pipe redirection
• command1 | command2
-> use the output from command1 as input
to command2
& Command – run command in background
• command1 &

Unix Overview

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Working With Unix

Basic Commands

Basic Commands

The following tables list some of the
available Unix commands with their
usage and examples.

Unix Overview

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Basic Commands
File Commands

cat

Usage: Display a files contents to the screen
Example: cat myfile
-> list file on screen

chgrp

Usage: Change group ownership of a file
Example: chgrp newgroup filename

chmod

Usage: Change permissions of a file
Example: chmod 777 myfile
-> use octal
chmod rwxr--r-- myfile -> use permissions
chmod u=rwx,g=r,o=r -> use each group
chmod a=rwx
-> use all group

cp

Usage: Copy files
Example: cp oldfile newfile

Basic Commands
File Commands

Unix Overview

cd

Usage: Change directories
Example: cd
-> go to home directory
cd ..
-> go back 1 directory
cd /…./
-> change directory path

ls

Usage: List directory contents
Example: ls
-> list file names
ls –a
-> list all files
ls –l
-> list file attributes
ls –r

-> reverse order
ls –t
-> based on modification
ls –alrt
-> combination

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Basic Commands
File Commands

mkdir

Usage: Create a directory
Example: mkdir newdir

mv

Usage: Rename file
Example: mv oldfile newfile -> renames to newfile

pwd

Usage: Print working directory
Example: pwd

rm

Usage: Remove a file

Example: rm oldfile

rmdir

Usage: Remove a directory
Example: rmdir

touch

Usage: Create an empty file
Example: touch newfile

Basic Commands
Process Commands

Unix Overview

ps

Usage: Show processes and their PID
Example: ps
-> show my processe
ps –ef
-> show all processes

kill

Usage: Send signal to process
Example: kill -20 <PID> -> suspend process <PID>
kill -9 <PID> -> stop process <PID>

&

Usage: Run command in background
Example: command1 &

<ctrl>z

Usage: Suspend a running process to regain the
Unix prompt

<ctrl>d

Usage: End of input
Usage: Alternate way to logout

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Basic Commands
Miscellaneous Commands

clear

Usage: Clear screen
Example: clear

df

Usage: Display disk information

Example: df

diff

Usage: Display file differences
Example: diff myfile yourfile

exit

Usage: End Unix session
Example: exit

find

Usage: find a file name – start in this directory and
find a file named “myfile” and print the path to it
Example: find . –name “myfile” -print

finger

Usage: Check for active users or user existence
Example: finger
finger accountName

Basic Commands
Miscellaneous Commands

Unix Overview

grep

gzip

Usage: find specified text in files

gunzip

Usage: Restore compressed files

history

Usage: Display list of commands
Example: history

man

Usage: Invokes Man Help Pages
Example: man cp

more

Usage: Display first page of file to screen and the use
<enter> to display more. <ctrl>c return to prompt
Example: more myfile

Usage: Compress a set of files.
Compressed file extension .tar.gz

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Basic Commands
Commands

Unix Overview

passwd

Usage: changes password – follow prompts
Example: passwd

w

Usage: Gives summary of users
Example: w

wc

Usage: Counts number of lines, words, bytes
Example: cat myfile | wc
-> lines, bytes, words
who | wc –l
-> number users
ps –e | wc –l
-> number of processes

who

Usage: Displays list of active users
Example: who

whoami

Usage: Displays logon ID
Example: whoami

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