unitproc/bkt-printl

   1 #!/bin/bash
   2
   3 function printl() {
   4     function yell() { echo "$0: $*" >&2; } # print script path and all args to stderr
   5     function die() { yell "$*"; exit 111; } # same as yell() but non-zero exit status
   6     function showUsage() {
   7         # Desc: Display script usage information
   8         # Usage: showUsage
   9         # Input: none
  10         # Output: stderr
  11         yell "USAGE:";
  12         yell "printl [int] [int] ([path])";
  13         yell ""
  14         yell "EXAMPLE:"
  15         yell "printl 5 17 somefile.txt"
  16     }; # Display information on how to use this script.
  17     function main() {
  18         # Desc: Prints ranges of lines
  19         # Usage: printl [int] [int] [path]
  20         # Version: 0.0.1
  21         # Example: printl 5 17 somefile.txt  # prints lines 5-17
  22         # Depends: Bash 5.1.16
  23         start="$1";
  24         end="$2";
  25
  26         # Require first two args be integers
  27         re='^[0-9]+$';
  28         if [[ ! "$start" =~ $re ]]; then
  29             showUsage;
  30             die "FATAL:First argument (start line number) not an integer:$(declare -p start)";
  31         fi;
  32         if [[ ! "$end" =~ $re ]]; then
  33             showUsage;
  34             die "FATAL:Second argument (end line number) not an integer:$(declare -p end)";
  35         fi;
  36
  37         # Require between 2 and 3 arguments are provided
  38         if [[ $# -ge 4 ]]; then
  39             showUsage;
  40             die "FATAL:Too many arguments:$#";
  41         fi;
  42         if [[ $# -le 1 ]]; then
  43             showUsage;
  44             die "FATAL:Too few arguments:$#";
  45         fi;
  46
  47         # Handle 3 argument case (int int file)
  48         if [[ $# -eq 3 ]] && [[ -f "$3" ]]; then
  49             # Use specified file
  50             input="$3";
  51         elif [[ $# -eq 3 ]] && [[ ! -f "$3" ]]; then
  52             showUsage;
  53             die "FATAL:Third argument not a file.";
  54         fi;
  55
  56         # Handle 2 argument case (int int)
  57         if [[ $# -eq 2 ]]; then
  58             # Use stdin
  59             input="-"
  60         fi;
  61
  62         # Print lines
  63         tail -n+${start} "$input" | head -n$((end - start + 1));
  64
  65     }; # main program
  66
  67     ( must main "$@" );
  68 };