Bash – View text file and highlight numbers

bashgedittext;

I'd like to view a text file on the terminal and highlight its numbers. Something like I get when I open it with gedit.
I haven't been able to do this with less, cat, vim or other viewers/editors.

P.S. My question is straightforward, but I haven't been able to find the correct keywords for a meaningful search.

DIY solution

Solution A

Match every number and highlights it, print every line:

egrep --colour=always '[-+]?[0-9]*[\.e]?[0-9]|$'

I guess I'll simply alias this.
I'm still wondering if there's a default option.

Edit: adding support for exponential e, tnx to @αғsнιη.

Solution B

Alright, my final solution below

grep -P --colour=always '(?:^|(?<=[\\, ;\-\+\*\/]))[-+]?[0-9]*[\.eE]?[0-9]+|$'

It looks behind for separation characters or beginning of line, and matches a great deal of number formats and the end of the line (so that every line is printed).

Finally, two useful aliases view and less-view:

alias v="grep --colour=always -P '(?:^|(?<=[\\, ;\-\+\*\/]))[-+]?[0-9]*[\.eE]?[0-9]+|$'"
function lv {                                                                    
    v $1 | less -R                                                               
}

Solution C

Here a better regex expression (to use within the single quotes of Solution B):

(?<![\w\.])[-+]?[0-9]*[\.eE]?\-?[0-9]+|$

This solution accounts for any non alphanumeric and dot separation symbols.
The previous one was lacking of generality.

Edit: adding -nT to grep shows aligned line numbers.
Edit2: account for negative exponents by adding \-?.

TL;DR

Paste this in your ~/.bashrc and use the v, lv, cv to view, less-view, and column-view your text files:

# Highlight numbers when displaying text files
alias v="grep --colour=always -nTP '(?<![\w\.])[-+]?\-?[0-9]*[\.eE]?[0-9]+|$'"
# Send v output to less
function lv {
    v $1 | less -R
}
# Convert CSV to TSV and send to lv
function cv {
    column -ts, $1 | lv
}

Edit: add CSV file reading shortcut and comments.

Best Answer

Match also +/- signs and e as well.

 grep -E --color '[-+\.]?[0-9](|[eE][-+]?[0-9]|$)'

This will match below various of numbers.

Related Solutions

Text – View File Containing DOS Text and Escape Sequences

That's MSDOS charset.

Try recode cp437..u8 in a UTF8 terminal.

It gives:

██▀▀▀▀▀▀ ██▀▀▀▀▀█  █▀▀▀▀▀█ ██▀▀█▀▀█ ██       █▀▀▀▀▀█ ██▀▀█ ██ ██▀▀▀▀▀▄
██▄▄▄▄▄▄ ██▄▄▄▄▄█  █▄▄▄▄▄█ ██ ██ ██ ██       █▄▄▄▄▄█ ██ ██ ██ ██    ██
      ▄█ ██        █    ▄█ ██    ██ ██       █    ▄█ ██ ██ ██ ██    ██
▄▄▄▄▄▄▄█ ██        █     █ ██    ██ ██▄▄▄▄▄  █     █ ██ ██▄▄█ ██▄▄▄▄▄▀

in colour.

Bash – Multicolored Grep

Here's a different approach. I have a little Perl script which I have already posted in another answer that will highlight the user provided patterns in different colors. A slightly modified version of the script will act like grep:

#!/usr/bin/env perl
use Getopt::Std;
use strict;
use Term::ANSIColor; 

my %opts;
getopts('hic:l:',\%opts);
    if ($opts{h}){
      print<<EoF; 
Use -l to specify the pattern(s) to highlight. To specify more than one 
pattern use commas. 

-l : A Perl regular expression to be colored. Multiple expressions can be
     passed as comma separated values: -l foo,bar,baz
-i : makes the search case sensitive
-c : comma separated list of colors;

EoF
      exit(0);
    }

my $case_sensitive=$opts{i}||undef;
my @color=('bold red','bold blue', 'bold yellow', 'bold green', 
       'bold magenta', 'bold cyan', 'yellow on_blue', 
       'bright_white on_yellow', 'bright_yellow on_red', 'white on_black');
if ($opts{c}) {
   @color=split(/,/,$opts{c});
}
my @patterns;
if($opts{l}){
     @patterns=split(/,/,$opts{l});
}
else{
    $patterns[0]='\*';
}

# Setting $| to non-zero forces a flush right away and after 
# every write or print on the currently selected output channel. 
$|=1;

while (my $line=<>) 
{ 
    my $want=0;
    for (my $c=0; $c<=$#patterns; $c++){
    if($case_sensitive){
        if($line=~/$patterns[$c]/){
           $line=~s/($patterns[$c])/color("$color[$c]").$1.color("reset")/ge;
           $want++;
        }
    }
    else{
        if($line=~/$patterns[$c]/i){
          $line=~s/($patterns[$c])/color("$color[$c]").$1.color("reset")/ige;
          $want++;
        }
      }
    }
print STDOUT $line if $want>0;
}

If you save that script as cgrep somewhere in your PATH and make it executable, you can specify up to 10 different patterns, each of which will be printed in a different color:

enter image description here

$ cgrep -h
Use -l to specify the pattern(s) to highlight. To specify more than one 
pattern use commas. 

-l : A Perl regular expression to be colored. Multiple expressions can be
     passed as comma separated values: -l foo,bar,baz
-i : makes the search case sensitive
-c : comma separated list of colors;