unix - shell prints line shell -

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write script named print_lines.sh uses head , tail print out specific set of lines file. script should take 3 arguments: line number start at, line number stop at, , file use. here's example run:

[user@localhost ~]$ print_lines.sh 7 10 /etc/passwd shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown halt:x:7:0:halt:/sbin:/sbin/halt mail:x:8:12:mail:/var/spool/mail:/sbin/nologin operator:x:11:0:operator:/root:/sbin/nologin

in example, script prints line 7 through 10 (inclusive) of /etc/passwd file. script must error checking. specifically, need check following things:

  • you right number of arguments (3).
  • the file specified exists , normal file.
  • the first line number specified less or equal last line number specified.
  • the actual number of lines in file greater last line printed.
  • if of conditions not true, should print appropriate error message user , stop. if met, you'll need bit of arithmetic , use head , tail print out lines requested.

this work not working good

filename=$1 firstline=$2 lastline=$3  i=0 exec <${filename}  # redirect file our stdin while read ;    # read each line reply variable     i=$(( $i + 1 ))  # maintain line count      if [ "$i" -ge "${firstline}" ] ;         if [ "$i" -gt "${lastline}" ] ;             break         else             echo "${reply}"         fi     fi done


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