UNIX Command: Looking into files.

file - to identify file types
head- peak at the first few lines
tail - view last few lines
cat - view contenst of file
more - view larger files.


file:
A program that can easily offer you a good hint as to the contents of a file by looking at the first few lines. The disadvantage of this commnad is, it is not 100% accurate
eg:- A text file has executable permission and the initial contents of the files look like a C program the file command interpret it as an executable program rather that an english text file.

% file newtext.txt helloworld.txt 'shiyas resume.doc'
newtext.txt: ascii text
....
...
photos: directory

% file *
will analyze all files in home directory
 
head: Use it to view up to the first few hundred lines of a very long file, actually. You can specify the number as well.
% head newfile.txt
first few lines are displayed

% head -4 newfile.txt
first 4 lines are displayed

Can supply multiple files as well
% head -4 newfile.txt passwd
=====>passwd<====
......................................

=====>newfile.txt<===
.......................................


Can be used along with pipes (|):
% who | head -5
the output of who is supplied to head -5 and lists down first 5 users in the list.


tail:
Provide last lines of the file.

combine the two, head and tail, so you can see just the tenth, eleventh, and twelfth lines of a file?

%

cat:
flags: -v -shead -12 .cshrc | tail -3