compare date

let say file name is
'file_20040101.txt'
'file_20040802.txt'
'file_20041202.txt'
'file_20050101.txt"

where '20040101' is date for that file.
and todays date is 2006106.

how we compare the date?
where the ouput will remove file before december 2004?

in this case, 'file_20040101.txt', 'file_20040802.txt' will be remove and other file will remain in the directory.
pleaseeeeee.......

Not sure how to do the compare, but I think there's another way if the file names corelate to the last time the file was written to. You should be able to use find for this. Sometihng like

find /yourFilePath -name '*.txt' -mtime +TheNumberOfDaysYouWantToDelete -exec rm {} \\;


look at the man pages for find and you will probably find what you want there. This is for AIX, you may need to modify a little for other flavors.

Hi,

the way dynamicvb suggests is probably the best one. But if you must get the date from the file name you must make a little drill in shell programming. For instance:


#!/usr/bin/ksh
# Script to delete files older than the given date
# Tested under AIX

# Function to print the digital substring from the first parameter
get_date() {
echo $1 |
awk '
{ if (match($0, "[0-9][0-9]*"))
print substr($0, RSTART, RLENGTH)
}
'
}

# Here we go
[ $# -eq 1 ] || {
echo "$0: usage: $0 date_limit" >&2
exit 1
}

LIMIT=$( get_date $1 )

# You should test the given parameter, here the length test only
# Bad parameter can cause a disaster, rm is irreversible!!
LENGTH=$( expr $LIMIT : [0-9][0-9]* )
[ $LENGTH -ne 8 ] && {
echo "$0: bad date limit given: $1" >&2
exit 1
}

# You must be in the appropriate directory (do cd ... first)
# or change the following find accordingly
find . -name "file_*.txt" |
while read F; do
DATE=$( get_date $F )
[ "$DATE" -lt "$LIMIT" ] && {
# Here echo the command only. After testing, uncomment following line
# rm $F
echo rm $F
}
done


Good luck