Find Digit in Filename & Bulk Rename

Extracted from StackOverflow: https://stackoverflow.com/questions/428109/extract-substring-in-bash

Generic solution where the number can be anywhere in the filename, using the first of such sequences:

number=$(echo $filename | egrep -o '[[:digit:]]{5}' | head -n1)

Another solution to extract exactly a part of a variable:

number=${filename:offset:length}

If your filename always have the format stuff_digits_... you can use awk:

number=$(echo $filename | awk -F _ '{ print $2 }')

Yet another solution to remove everything except digits, use

number=$(echo $filename | tr -cd '[[:digit:]]')

I need to loop through the directory and take the filename and crop off the name assuming that the first 6 numbers are the ID number then change it to the final form.  I had to ignore all the spacing and junk after the number and just made the assumption that all I needed was the numbers in front of the file.

find . -print0 | while read -d $'\0' file; do number=$(echo $file | egrep -o '[[:digit:]]{6}' | head -n1); mv ${number}* ${number}.jpg ; done

I had some problems with files with the hyphen.

ls > /tmp/list

I needed to export a list of file then manipulate with VIM, keeping only the first work in each line then use the file list to iterate through

:1,$s/\(\s*\w\+\).*/\1/g

for x in `cat /tmp/list`; do  number=$(echo $x | egrep -o '[[:digit:]]{6}' | head -n1); mv ${number}* ${number}.jpg; done 

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