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I am a big fan of one-liners using sed awk perl and other tools. But there are that are things hard to do in one-liner, such as when you working with a CSV file and there are commas between quotes, or when you want to print a centralized field with printf.

A few months ago I wrote ftable more for fun than anything else, but last weekend I took it seriously and created a GitHub repository and a tutorial for it.

ftable tutorial
ftable code

Questions

Do you know of a tool that's similar to ftable? I hate feeling like re-inventing the wheel.

As I am not programmer (I am sysadmin/devops). Is there anybody willing to review the code and spot my endless mistakes?

#! /usr/bin/env perl
# Author: Tiago Lopo Da Silva
# Date: 20/10/2013
# Purpose: Print formatted table

use strict;
use warnings;
use POSIX;
use Switch;
use Getopt::Long qw(:config no_ignore_case);
use Data::Dumper;

our $comma="<comma>";
our $dollar="<dollar>";
our $pipe="|";
our $plus="+";
our $minus="-";
our $FS=',';
our $nb=0;

my %h;
if ($#ARGV >= 0){
my $lf; my $cf; my $rf; my $print;

GetOptions( 'l|left:s' => \$lf,
             'r|right:s' => \$rf,
            'c|center:s' => \$cf,
                'p|print:s' => \$print,
            'F:s' => \$FS,
                'n|noborder' => \$nb,
           ) || print_usage();

%h=get_details($lf,$cf,$rf,$print);
}else {
%h=get_details();
}
print_table(\%h);

sub get_quoted_fields {
# this sub finds quoted fields
    my $str1 = $_[0];
    my $qf;
    while ( $str1 =~ /(["'].*?["'])/ ){
        $qf.="$1${comma}";
        $str1 =~ s/$1//;
    }
    return $qf;
}

sub get_translated {
    my $qf = $_[0];
    my $str= $_[1];
    my @arr;
    my %h;

    if (defined ($qf)) {
        @arr = split(/$comma/,$qf);
    }

    foreach my $i ( @arr ){
        my $tmpvar=$i;
        $i =~ s/$FS/$comma/g;
        $h{$tmpvar} = $i;
    }

    while ( my($key,$value) = each(%h) ){
        $key =~ s/\$/\\\$/g;
        eval "\$str =~ s/$key/$value/g; ";
    }

    return $str;
}

sub special_split {
#This sub splits strings but taking quoted fields in consideration
    my $str=$_[0];
    $str =~ s/\$/$dollar/g;
    $str =~ s/\(/<op>/g;
    $str =~ s/\)/<cp>/g;
    $str =~ s/\//<slash>/g;
    my $str1=$str;
    my $qf;
    my @a;

    $qf=get_quoted_fields("$str1");

    my $translated = get_translated($qf,$str);

    @a = split (/$FS/,$translated);

    foreach my $i ( @a ){
my $safe_fs=$FS;
switch($safe_fs) {
case '\.' {$safe_fs =~ s/\\//g;}
case '\t' {$safe_fs =~ s/\\t/\t/g;}
case '\s' {$safe_fs =~ s/\\s/ /g;}

}

            $i =~ s/$comma/$safe_fs/eg;
            $i =~ s/$dollar/\$/g;
            $i =~ s/<op>/\(/g;
            $i =~ s/<cp>/\)/g;
            $i =~ s/<slash>/\//g;
            $i =~ s/["']//g;
            $i =~ s/\s+/ /g;
    }

    return @a;
}

sub fill_str {
# This sub fills the string with padding chars
my $f_char=$_[0];
my $f_times=$_[1];
my $str;
$str="$f_char"x$f_times;
return $str;
}

sub print_border {
# This sub prints horizontal border
my @length=@{$_[0]};
foreach my $i (@length){
unless (defined($i)){$i=1;}
print "$plus";
my $counter=0;
while ( $counter < ($i+2) ){
print "$minus";
$counter++;
}
}
print "$pipe\n";
}

sub print_left {
#This sub prints fields with proper padding in the left side.
#It takes two args, 1st length of the maximun field and field content.
my $length=$_[0];
my $col=$_[1];
unless (defined($length)){ $length="";}
unless (defined($col)){ $col="";}
my $str="printf ' %-".$length."s ','".$col."';";
eval $str
}

sub print_right {
#This sub prints fields with proper padding in the right side.
#It takes two args, 1st length of the maximun field and field content.
my $length=$_[0];
my $col=$_[1];
unless (defined($length)){ $length="";}
unless (defined($col)){ $col="";}
my $str="printf ' %".$length."s ','".$col."';";
eval $str
}

sub print_center {
#This sub prints fields with proper padding in the both sides.
#It takes two args, 1st length of the maximun field and field content.
my $length=$_[0];
my $col=$_[1];
my $str;
unless (defined($length)){ $length=1}
my $cl=length($col);
my $padding=(($length - $cl)/2);
        my $lp; my $rp;
if ( (($length - $cl) % 2 ) == 0 ){
$lp=$padding;   
$rp=$padding;   
}else{
$lp=ceil($padding); 
$rp=floor($padding);    
}

my $l_str ; my $r_str;
$l_str=fill_str(" ",$lp);
$r_str=fill_str(" ",$rp);
$str="printf ' %".$length."s ','".$l_str.$col.$r_str."';";
eval $str;
}

sub get_details {
# This subs creates a hash containg the whole content of the table, alignment info and
# number of columns/ fields
my @align = get_align($_[0],$_[1],$_[2]);
my @print = get_print($_[3]);
my @content;
my @tmp_arr;
my @tmp_arr2;
my @length;
my $n_col=0;
my $counter=0;

my $p_print;
if(@print){ $p_print=1; }else{ $p_print=0;}

while (<>){
@tmp_arr= special_split("$_");
unless( $p_print ){
for ( my $i=0 ; $i <= $#tmp_arr; $i++){
$print[$i]=$i;  
}
}
my $counter2=0;
foreach my $i (@print){
$tmp_arr2[$counter2] = $tmp_arr[$i];
$counter2++
}
$counter2=0;
foreach my $i (@tmp_arr2){
defined($i) && $i =~ s/^\s+//;
defined($i) && $i =~ s/\s+$//;
$content[$counter][$counter2] = $i;
my $li= length($i);
if ( defined( $length[$counter2] ) ){
if( $li > $length[$counter2] ) {
$length[$counter2]=$li;
}
}else{
$length[$counter2]=$li;
}   
$counter2++;
}
if ( $counter2 > $n_col ){ $n_col=$counter2;}
$counter++;

}

my %details= (
content => \@content, # content of the file
length => \@length, # Maximun length of fields
align => \@align, # Alignment
n_col => $n_col, # Maximun number of columns/fields
);

return %details;
}


sub print_table{
my %h = %{$_[0]};
my @content=@{$h{"content"}};
my @length=@{$h{"length"}};
my @align=@{$h{"align"}};
my $n_col=$h{"n_col"};
my $counter=0;

foreach my $line (@content){
$nb || print_border(\@length);
my $str;
my $counter2=0;
for ( my $i=0; $i < $n_col ; $i++ ){
my $col = $content[$counter][$i];
unless (defined($col)) { $col = ""}
$col =~ s/"//g;
$col =~ s/'//g;
my $l=$length[$counter2];
$nb || print "$pipe";

my $left="false"; my $right="false";
my $center="false";
switch ($align[$counter2]){
case "l" { $left="true";}
case "r" { $right="true";}
else { $center="true";}
}

if ( $right eq "true" ){
print_right($l,$col);
}
if ( $left eq "true" ){
print_left($l,$col);
}

if ( $center eq "true" ){
print_center($l,$col);
}

$counter2++;
}
unless ($nb) {print "$pipe\n"}else{print "\n"}
$counter++;
}
$nb || print_border(\@length);
}

sub get_align {
# This sub creates an array with the alignment information
my $lf = $_[0];
my $cf = $_[1];
my $rf = $_[2];
my @align;

defined($lf) && (my @lf = split (/,/,$lf));
defined($cf) && (my @cf = split (/,/,$cf));
defined($rf) && (my @rf = split (/,/,$rf));

foreach my $i (@lf){
$align[$i] = "l";   
}

foreach my $i (@cf){
$align[$i] = "c";   
}

foreach my $i (@rf){
$align[$i] = "r";   
}
shift(@align);
return @align;
}

sub get_print {
# This sub creates an array containing the field numbers to be printed
my $print = $_[0];
my @print;
defined($print) && (my @a = split(/,/,$print));
my $counter=1;
foreach my $i (@a){
$print[$counter] = $i-1;
$counter++;
}
shift(@print);
return @print;
}

sub print_usage {

my $usage = << 'EOF';
Usage: ftable [OPTIONS] [FILE]

Options:
  -l, --left
        List of field numbers (separated by comma) to be left aligned

  -r, --right
        List of field numbers (separated by comma) to be right aligned

  -c, --center
        List of field numbers (separated by comma) to be center aligned
        It is default if no alignmnet provided

  -p, --print
        List of field numbers (separated by comma) to be printed and ordered

  -n, --noborder
        Do not print border

  -F, --field-separator
        Field separator, if no specified "comma" (,) is the default value

Examples:

        ftable -F ':' -p 3,1,6 /etc/passwd
        ftable -l 1 -c 2,3 -r 4 /tmp/table.csv
        ftable -n -F ':' /etc/passwd
EOF
print $usage;
exit 2;
}
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3 Answers 3

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column(1) is a Unix tool with a similar purpose, but does not draw box borders using ASCII art.

There may not be a standard command to draw tables with box borders, but as always, there's a CPAN module for that. As for parsing the input, there's a CPAN module for that too. By taking advantage of CPAN, you can avoid and discard most of your code.

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  • \$\begingroup\$ column does not align the fields, and does not allow you to order the fields neither. I am aware of CPAN but the idea is to keep it easy to install even when older version of Perl is installed. But thanks I appreciate your suggestions. \$\endgroup\$
    – Tiago
    May 26, 2014 at 21:36
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I understand your desire to use only core Perl modules, but be aware that parsing CSV is hard. There's a lot of potential gotchas, and home-grown solutions pretty much never handle them properly. For example, what happens if there are embedded quotes inside a quoted field? Or a newline inside a field?

I think the tool is potentially useful, but I would strongly urge you to use Text::CSV (or similar). It will be faster, most robust, and more maintainable. And it won't be reinventing that part of the wheel.

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Since you prefer not to use CPAN modules, have a look at Perl formats. The format function is part of Perl 5. It allows you to specify a template for the table, and then you can fill it in with values.

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