Imitate head and tail command script

Shell Programming and Scripting
1

Hi,

I have been given assignment of 30 scripts out of which I was able to solve many, I need help with few out of which one asks to imitate head and tail command of unix without using the head and tail commands. Problem is stated below:

Write an interactive shell script to imitate the head and tail commands in unix.Dont use head and tail command and provide appropriate switch.

Can anyone please help me with that?

2

Sounds like a homework thing?

Anyway.

Interactive = read
Cat
wc for finding out how many lines there are
A handful of other commands
Awk for everything else

FILE=$1

echo "How many lines?: "
read HowMany

echo "Heads or tails? "
read HoT
case "$HoT" in
  h) awk 'NR <= '$HowMany $FILE ;;
  t) awk 'NR > '$(($(wc -l < $FILE) - $HowMany)) $FILE
esac

(there's a distinct lack of error checking here! $1 is the filename when calling this as a script from the command line)

3

Thanks it helped, I just needed to replace "file" with $FILE

yes, its an assignment more like a exam i will be having and I need to pass it :slight_smile: I dont intend to code for my job :slight_smile:

Thanks again.

4

Yes, I saw it.

Good luck!

5

since your question is "imitate head/tail without using head/tail" and nothing else, then you can use other language to do that. awk, Python, Perl..etc.

6

I have got it working with scott's help :slight_smile:

Thanks for replying.