Expand a range of numbers with grep - shell

Question

I work in telecoms and regularly need to expand number ranges.
For example, 6121234567X [note that there are 10 numbers preceeding the X] is shorthand for:
61212345670
61212345671
61212345672....... etc (a 10 number range)
and 612123456X [note that there are only 9 numbers preceeding the X] is shorthand for
61212345600
61212345601....... etc (a 100 number range)
So I need a grep command that...
reads how many characters in the line preceeding the X (to determine how many suffixes)
writes the appropriate amount of lines (10, 100, or 100) with ascending suffixes
hopefully removes the original line

Answer 1

Below is the Python script that does it, file-name is the expected first argument. Example usage: python script.py file.in > file.out
#!/usr/bin/env python
import sys
def generate(pattern):
p = pattern.lower().find('x')
ret = ""
for i in range(10**(10-p+1)):
ret += pattern[:p] + str(i).zfill(10-p+1) + " "
return ret
if __name__ == "__main__":
if len(sys.argv) <= 1:
print("Filename needed!")
else:
with open(sys.argv[1]) as f:
for ln in f:
print(generate(ln.rstrip()))

Answer 2

You can do this in awk quite quickly:
awk -v val=$a -v max=10
'BEGIN {
gsub("X","",val)
items=max - length(val)
for (i=0; i<=10^items; i++)
print val*(10^items)+i
}'
This works as an example. To do the same reading from a file, you just need to play with $1 (first field of the field) instead of val and move all the code from BEGIN into the main block.
Explanation
-v val=$a -v max=10 pass parameters: $a is the variable containing the string on the form 12345678X AND max contains the maximum amount of digits the number will have (10 in your case).
BEGIN {} perform all these actions [before/without] reading a file.
gsub("X","",val) remove X from val.
items=max - length(val) count the size of the variable without the X.
for (i=0; i<=10^items; i++) print val*(10^items)+i loop from 0 to 10^remaining_size. This means from 0 to 10 or from 0 to 100... depending on the result of 10 - size without X.
Test
With 9 as maximum:
$ a=12345678X
$ awk -v val=$a -v max=9 'BEGIN {gsub("X","",val); items=max - length(val); for (i=0; i<=10^items; i++) print val*(10^items)+i}'
123456780
123456781
123456782
123456783
123456784
123456785
123456786
123456787
123456788
123456789
123456790

Answer 3

echo 6121234567X | perl -nE 'm/(.*)X/;
say $1. $_ foreach (0..10**(11-length $1)-1)'
61212345670
61212345671
61212345672
61212345673
61212345674
61212345675
61212345676
61212345677
61212345678
61212345679
It's a little uglier to get the zero padded format:
echo 611234567X | perl -wne 'm/(.*)X/; $b=$1; $r=11 - length $b;
$fmt="%0" . $r . "s\n";
printf "$b$fmt", $_ foreach (0..10**$r-1) '