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Imitate head and tail command script


 
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# 1  
Old 10-23-2009
Imitate head and tail command script

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  
Old 10-23-2009
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

Code:
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)

Last edited by Scott; 10-23-2009 at 10:16 PM.. Reason: wc < file => wc < $FILE
# 3  
Old 10-23-2009
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 Smilie I dont intend to code for my job Smilie

Thanks again.
# 4  
Old 10-23-2009
Yes, I saw it.

Good luck!
# 5  
Old 10-23-2009
Quote:
Originally Posted by nutalk
Dont use head and tail command and provide appropriate switch.
Can anyone please help me with that?
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  
Old 10-23-2009
I have got it working with scott's help Smilie

Thanks for replying.

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