Validating File Name format in linux shell

This tests every file in the current directory, using bash's [[ operator, against the pattern:

• start of string ^
• 3 digits
• -
• 8 digits
• -
• 9 digits
• .pdf
• end of string $
• that the middle 8 digits evaluate to a valid date according to GNU date

You can adjust the assumptions above easily enough.

for f in *
do
  [[ $f =~ ^([0-9][0-9][0-9])-([0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9])-([0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]).pdf$ ]] && 
  date -d ${BASH_REMATCH[2]} &>/dev/null && 
  echo Valid: "$f"
done

sounds like:

TOCHECK=( "01-20170228-12345678" "012-20170230-012345678" "01-20170228-12345678" "123-20170730-012345678" )

for CHECK in $(seq 0 $(( ${#TOCHECK[@]}-1 )) ); do
    PARTS=( $(echo ${TOCHECK[$CHECK]} | sed "s/-/ /g")   )   
    echo -ne "\nchecking "
    echo "\"${PARTS[@]}\""
    echo "\"${PARTS[0]}\""
    echo "\"${PARTS[1]}\""
    echo "\"${PARTS[2]}\""

    if echo ${PARTS[0]} | grep "[0-9]\{3\}" ; then
        echo first part ok
    fi

    if echo ${PARTS[2]} | grep "[0-9]\{9\}" ; then
        echo last part ok
    fi  

    date --date="${PARTS[1]}"
    RES=$?
    echo $RES
    if [ 0$RES -eq 0 ]; then
        echo date OK
    fi  
done

(just some conceptual idea, of course to be modified)

It's not enough to use regexps. The validation is 2 steps: regexp matching and date validation. Here's a Python implementation:

from __future__ import print_function
import sys 
import re
import datetime

def validate(filename):
    match = re.match(r"[0-9]{3}-([0-9]{8})-[0-9]{8}\.pdf", filename)
    if not match:
        return False
    datestr = match.group(1)
    try:
        datetime.date(int(datestr[:4]), int(datestr[4:6]), int(datestr[6:8]))
    except ValueError:
        return False
    else:
        return True

if __name__ == "__main__":
    if validate(sys.argv[1]):
        print(":-)")
        sys.exit(0)
    else:
        print(":-(")
        sys.exit(1)

Usage: python validate.py FILE

One can probably use grep and date to do the same.

One basic solution, using grep. Doesn't do the detailed date checking aspect, instead merely checks it's numeric.

if ls|grep -vE '^[0-9]{3}-[0-9]{8}-[0-9]{8}\.pdf$'; then
    echo some bogus files found
else
    echo all good
fi