get directory mtime in unix time

In scripts when you need to compare last modification date of directories, you can get the date using stat in a unix timestamp or seconds from the Epoch:

# stat -c '%Z' /usr/local/sbin
1373673278

Using date you can get the same format like this:

# date +%s
1373673486

You could use this in a script to do something if a directory is older or newer than some amount of time:

#!/bin/bash
# FILE: sync_usr_local_sbin.sh
# AUTHOR: ForDoDone <fordodone at email.com>
# DATE: 2013-07-12
# NOTES: syncs /usr/local/sbin to hostxyz if it's been modified in the last 5 minutes
#

now=`date +%s`

uls_lastmtime=`stat -c '%Z' /usr/local/sbin`

uls_diff=$(echo $now - $uls_lastmtime |bc)

if [ $uls_diff -lt 300 ]
then
  rsync -a /usr/local/sbin/ hostxyz:/usr/local/sbin
fi

Of course rsync has a bunch of options to check whether it needs to do an update of files, this is just an example.

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check if a directory is a nfs mount

Use stat to display the file system status, following links, and output the format as the human readable file system type:

#stat -f -L -c %T /tmp
ext2/ext3
#
# stat -f -L -c %T /mnt/fileserver/volume
nfs
#

As suspected “/tmp” is a regular ext file system, but the path “/mnt/fileserver/volume” is an nfs mount. What happens if we unmount the nfs mount:

# umount /mnt/fileserver/volume
#
# stat -f -L -c %T /mnt/fileserver/volume
ext2/ext3
#

It reports properly that the directory is just an unmounted directory in a regular ext file system.

Alternatively you can use the mountpoint command:

# mountpoint /tmp
/tmp is not a mountpoint
#
# mountpoint /mnt/adfs40/vol1
/mnt/adfs40/vol1 is a mountpoint
#
# umount /mnt/fileserver/volume
# mountpoint /mnt/adfs40/vol1
/mnt/adfs40/vol1 is not a mountpoint
#
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