How to read only 1st three character from a file using sed in unix

Shell Programming and Scripting
1

Hi
can any one please help me how to read forst three character from a file using sed or any other way

example

My file contains data like this

asd123#412

I want to just read 1st three characters no matter whatever it is (character, digit, special characters, space, tab..etc)

Thanks in advance

2 
[house@leonov] FULL='asd123#412' ; PART=${FULL:0:3} ; echo $PART
asd
3 
sed 's/\(.\{3\}\).*/\1/' file
4

Why can you not use cut?

cut -c1-3  filename

Sounds like homework to me.....

5

Few more:

awk '{print substr($0,1,3)}' file

perl -lne '/(.{3}).*/ and print $1' file

perl -lne '/(...).*/ and print $1' file

perl -lne 'print substr($_,0,3)' file

perl -lne '@x=unpack("A3"); print $x[0]' file

tyler_durden

6

Thank u very much,

Can u pls throw some light over it.

7

Taking this task literally, any program which knows about records is not suitable. We need to read the raw file.

My solution to getting the first three characters of a file no matter what they are is:

dd bs=3 count=1 if=input_file of=output_file

We have avoided putting the characters in a shell variable because we don't know what they are.
Program "cut" is unsuitable if one of the characters is a linefeed for example.