Background
End of Year, Beginning of a new year, and end of Month are often good times to stress a computer system.
We have had our systems stressed these last couple of months.
Often it is running low on disk space, a lot of higher than normal database backup and log backups.
MS Windows
Microsoft Tools
On Windows I will often use Microsoft’s own Computer Management to review disks logical size and utilization.
Or File Explorer and filter by size looking for huge ones.
Space Sniffer
Or better still SpaceSniffer.
I spoke about SpaceSniffer here.
Linux
I know I am avoiding talking about Linux.
And, so let us talk about Linux a bit.
du command
Introduction
I suppose du means disk utilization.
Help
First let us get a quick overview of what du does and the options it offers.
Syntax
du --help
Output
Explanation
What does it do?
Summarize disk usage of each FILE, recursively for directories.
Options Tabulated
| Option | Meaning | Usage |
|---|---|---|
| -a | List files as well, not just directories | Usage is du -a |
| -B | Block Size | -b 1 is default -b 1024 means to divide the actual size by 1 K |
| -h | Human readable | usage is du -h |
| –exclude=PATTERN | Exclude files based on certain filename or extension | du -a -B 1 -h –exclude=*.gz /dbbackup |
| –max-depth | Our many folders down to go | du –max-depth=4 /dbbackup |
Sample
Block Size ( -B)
Sample ( Block Size at 1 )
du -a -B 1 /dbbackup | grep "sql"
Output
Explanation
- /dbbackup/gregory/export.sql is 4096
Sample ( Block Size at 1024 )
du -a -B 1024 /dbbackup | grep "sql"
Output
Explanation
- /dbbackup/gregory/export.sql
- was at 4096
- But, now is 4
- 4096/1024 => 4
Human Readable ( -h)
Sample ( Block Size at 1024 )
du -a -h *.sql
Output
Explanation
- /dbbackup/gregory/export.sql
- was at 4096
- But, now a more readable 4.0 K
exclude ( -exclude=filter)
Sample ( Exclude files already compressed via gzip )
du -a --exclude=*.gz
max-depth=N
Depth to show = 1
du --max-depth=1 -h /dbbackup
Output
Depth to show = 4
du --max-depth=4 -h /dbbackup
Output
Explanation
- In our first sample:
- We progressed down only one folder tree from our asking node ( /dbbackup )
- In our second example:
- We went down 4 levels from our root from /dbbackup
Use case scenario
Use case #1
Get Folder Size for our backup folder ( /dbbackup)
Baseline
Sample
du --max-depth=4 /dbbackup
Output
Silence Errors
There is an error for “permission denied“.
Let us silence it for now.
Sample
du --max-depth=4 /dbbackup 2>1 | grep -v 'permission denied'
Output
Explanation
- Using 2>1
- We redirect errors such as permission denied to standard output
- Using grep -v
- We filter out ‘permission denied’
Ordered Results
Let us order by size.
Sample
du --max-depth=4 /dbbackup 2>1 | grep -v 'permission denied' | sort -nr
Output
References
- StackOverflow
- Exclude all permission denied messages from “du”
Link
- Exclude all permission denied messages from “du”
