Get the newest file from directory structure year/month/date/time

Question

I store backups of databases in a directory structure

year/month/day/time/backup_name

an example would be

basics_mini/2012/11/05/012232/RATIONAL.0.db2inst1.NODE0000.20110505004037.001 basics_mini/2012/11/06/012251/RATIONAL.0.db2inst1.NODE0000.20110505003930.001

note that timestamp from the backup file cannot be used. Before the automation testing starts the server time is set to 5.5.2011

So the question is how I can get the latest file if I pass the "base directory" (basics_mini) to some function that I am going to code.

I need to restore the newest database. I do that in php but I wonder if there is a simple shell scripting solution.

Answer 1

find 'basics_mini' -type f | 
sed 's/.*basics_mini\///' |
sort -t '/' -k1nr -k2nr -k3nr -k4nr |
head -1

This will find files in your backup directory, then sed will strip the leading path (up until your year dir). Then, the sort will separate the pathname on '/' and perform a numerical sort on field 1, 2, 3 and 4, i.e., year, month, day and time. Finally, head -1 will return the top line of output.

Of course, this will only return 1 file even if there were multiple identical newest entries (if that's a concern for you).

Answer 2

With this naming scheme, the most recent backup is in the last subdirectory in lexicographic order. You can obtain the most recent directory directly in the shell, taking advantage of the fact that wildcards are expanded in lexicographic order.

cd basics_mini
set [0-9][0-9][0-9][0-9]/*/*/*
shift $(($#-1))
echo "The most recent backup is in $1"

In zsh, you can directly get the last directory with a glob qualifier.

echo "The most recent backup is in" basics_mini/[0-9][0-9][0-9][0-9]/*/*/*([-1])

Answer 3

find should suit your needs:

find "/path/to/backup_dir" -type f|sort -r|head -n1

This only works if you've got (as in your example) leading zeroes on your month and day folders

If you want a backup with a specific file name (or pattern) add a name pattern to the find parameters, e.g.

find "/path/to/backup_dir" -type f -name "*db2inst1*"|sort -r|head -n1

... or use -iname for case insensitive patterns

Now to the details of the above commands:

• find "/path" recursively lists all files/dirs in the given path (unless you use further filtering:
• the -type f parameter of find filters out everything that's not a regular file)
• -name or -iname match files according to a specific pattern
• sort sorts the output in reverse order (-r)
• head -n1 only prints the first line (-n 1) of its input and immediately exits after doing that.

Answer 4

My solution would be to use this. It will output the newest file possible:

ls -lcR --full-time | grep '^-' | sort -k 6 -r | head -n 1

Explanation:

ls -lcR

-l use a long listing format

-c show ctime (time of last modification of file status information)

-R list subdirectories recursively

grep for files starting with a - (dash), meaning 'regular-files'.

sort -k 6 -r

-k Sort by column n (6 as this holds the date field)

-r Reversed

head -n1

-n number of rows to display (from the top down. 1)