Solved

magic number in unix

Posted on 2000-02-22
5
1,178 Views
Last Modified: 2008-03-06
What is the magic number in unix???
0
Comment
Question by:bolotin
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
5 Comments
 
LVL 3

Expert Comment

by:RobWMartin
ID: 2547078
It is a known sequence of bytes that always show up in a file of a certain type.  You can usually assume that if the sequence shows up in the right spot in the file, you have a file of the given type.  For example, if the file starts with 0x000001b3 it is an MPEG video stream.  The information is usually kept in a magic file.  The "file" command uses it to identify files.

Rob
0
 
LVL 3

Expert Comment

by:RobWMartin
ID: 2547100
BTW:  you can look at the contents of the magic file to find the magic numbers of well-known file types.  Since the location of the magic file depends on the flavor of *nix you are using, try

find / -name 'magic'

Then pipe the file through the more command to look at it.

Rob
0
 

Accepted Solution

by:
cartoon022100 earned 50 total points
ID: 2550049
the file "/etc/magic" contains all magic numbers. the "file" command uses this magic number to compare with the contents in the file.depending upon the matching ,the file command gives output as ascii text  ot C file or binary file etc etc

"man magic" may help u more
Inigo
0
 
LVL 3

Expert Comment

by:RobWMartin
ID: 2554760
The magic file is not located at /etc/magic on all systems.
0
 
LVL 3

Expert Comment

by:RobWMartin
ID: 2616313
bolotin,

Hate to be pushy, but you need to decide who gave you the right answer first.  You can accept one of my comments as the answer, unless you feel cartoon gave you more useful info.
0

Featured Post

Enroll in May's Course of the Month

May’s Course of the Month is now available! Experts Exchange’s Premium Members and Team Accounts have access to a complimentary course each month as part of their membership—an extra way to increase training and boost professional development.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
Unix, date minus 1, 2 or 3 days (last working day) 11 95
unix scripting question 1 120
AIX 5.x set up arrow to recall 11 72
Expiration and Locking of Unix/Solaris OS Accounts 7 87
Let's say you need to move the data of a file system from one partition to another. This generally involves dismounting the file system, backing it up to tapes, and restoring it to a new partition. You may also copy the file system from one place to…
Introduction Regular patching is part of a system administrator's tasks. However, many patches require that the system be in single-user mode before they can be installed. A cluster patch in particular can take quite a while to apply if the machine…
Learn how to find files with the shell using the find and locate commands. Use locate to find a needle in a haystack.: With locate, check if the file still exists.: Use find to get the actual location of the file.:
Learn how to navigate the file tree with the shell. Use pwd to print the current working directory: Use ls to list a directory's contents: Use cd to change to a new directory: Use wildcards instead of typing out long directory names: Use ../ to move…

759 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question