filesystem-checks.md

Filesystem checks

Some of the basic disk utilities include commands like du, df, mount but these have several options that can be very helpful.

ls even has a few options that are useful but not always used.

ls -A             # same a -a but excludes . and .. from the output
ls -lSr           # sort by size in reverse order - so the bottom is the largest
ls -lArt          # sort all by last modified date in reverse order - so you see latest at the bottom. 
ls -ld directory  # use to see the information on the directory instead of its contents
ls -lb            # use to print any characters in a filename you don't usually see like spaces, tabs, etc" 

With du

# to get a summary of sizes of directories in the directory you're in
du -sh  *    
du -h -d 1 /dir   # similar to above, does a "depth" of 1 giving totals for the directories under /dir

However, if you have multiple filesystem types they can show a lot of data, but you can exclude (-x) them from your output. To see what type they are use the -T flag and then exclude that. If you have it wrong it won't exclude it (example: nfs vs nfs4)

df -h -x squashfs -x nfs4 

And if you have a filesystem you want to remount

mount -o remount

And who can forget find, lsof and others...

# find file or directory with case insensitive name
find /directory -iname "*name*"
# find file with case insensitive filename
find /directory -type f -iname "*filename*"
# find directory with case insensitive name
find /directory -type d -iname "*name*"
# find file (not directory) older than (+) 3 days.
find /directory -type f -mtime +3

If you've deleted a file but he application is still writing to it you can still read the data off of the file.

lsof 
lsof +D directory     # this tells you what applications are using files in that directory

Of course, if you now know that there are space issues and you need to expand disks you can look at filesystem expansion or maybe you need to move data across to another disk.