Data rotation and cleanup in Raspberry Pi - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is data rotation in the context of Raspberry Pi?

Data rotation means regularly moving or renaming old data files so new data can be saved without using too much space. It helps keep storage clean and organized.

beginner

Why is cleanup important after data rotation?

Cleanup removes old or unnecessary files after rotation to free up storage space and keep the system running smoothly.

beginner

Which Linux command is commonly used to delete old files during cleanup?

The rm command is used to delete files in Linux, including on Raspberry Pi.

intermediate

How can you automate data rotation and cleanup on Raspberry Pi?

You can write a script (like a Bash script) that renames or moves old files and deletes very old ones, then schedule it to run regularly using cron.

intermediate

What is a simple example of a data rotation script on Raspberry Pi?

A script that renames a log file to include the date, then creates a new empty log file for fresh data, and deletes logs older than a certain number of days.

What does data rotation help prevent on a Raspberry Pi?

A Hardware overheating

B Slower internet speed

C Running out of storage space

D Screen flickering

Data rotation helps prevent running out of storage space by managing old files.

Which tool schedules scripts to run automatically on Raspberry Pi?

A cron

B nano

C ssh

D ping

cron is used to schedule tasks automatically on Linux systems like Raspberry Pi.

What command deletes files in Linux?

A rm

B mv

C cp

D ls

rm deletes files, mv moves or renames, cp copies, and ls lists files.

What is a common file renamed during data rotation?

A System files

B Log files

C Executable programs

D Configuration files

Log files are often rotated by renaming to keep recent logs separate from old ones.

Why delete old files after rotation?

A To change file permissions

B To slow down the system

C To increase file size

D To free up disk space

Deleting old files frees up disk space and keeps the system efficient.

Explain how you would set up a data rotation and cleanup process on a Raspberry Pi.

Think about how logs are handled and how to automate tasks on Linux.

Describe why data rotation and cleanup are important for Raspberry Pi projects.

Consider what happens if storage is full or cluttered.

Practice

1. What is the main purpose of data rotation and cleanup on a Raspberry Pi?

easy

A. To keep storage organized and remove old files

B. To increase the CPU speed

C. To install new software automatically

D. To change the screen resolution

Solution

1. Step 1: Understand data rotation and cleanup

   Data rotation and cleanup help manage files by removing old or unnecessary data.

2. Step 2: Identify the main goal

   The goal is to keep storage organized and free space by deleting old files.

3. Final Answer:

   To keep storage organized and remove old files -> Option A

4. Quick Check:

   Data rotation = storage cleanup [OK]

Hint: Think about storage space and file management [OK]

Common Mistakes:

• Confusing data cleanup with hardware upgrades
• Thinking it changes system performance directly
• Assuming it installs software automatically

2. Which of the following commands correctly deletes files older than 7 days in the /var/log directory on Raspberry Pi?

easy

A. find /var/log -type d -mtime +7 -delete

B. find /var/log -type f -mtime +7 -delete

C. rm /var/log/* -mtime +7

D. delete /var/log -older 7

Solution

1. Step 1: Understand the find command syntax

   To delete files older than 7 days, use find with -type f (files), -mtime +7 (older than 7 days), and -delete.

2. Step 2: Check each option

   find /var/log -type f -mtime +7 -delete uses correct syntax. find /var/log -type d -mtime +7 -delete targets directories (-type d), not files. rm /var/log/* -mtime +7 uses rm incorrectly with -mtime. delete /var/log -older 7 is not a valid command.

3. Final Answer:

   find /var/log -type f -mtime +7 -delete -> Option B

4. Quick Check:

   find + -mtime +7 + -delete = correct [OK]

Hint: Use find with -type f and -mtime +days to delete old files [OK]

Common Mistakes:

• Using -type d instead of -type f
• Trying to use rm with -mtime option
• Using invalid commands like delete

3. What will be the output of this script snippet on Raspberry Pi?

logfile="/var/log/syslog"
backup="/var/log/syslog-$(date +%Y%m%d)"

mv $logfile $backup
> $logfile
ls /var/log/syslog*

medium

A. Only /var/log/syslog-YYYYMMDD file listed

B. Only /var/log/syslog file listed

C. /var/log/syslog and /var/log/syslog-YYYYMMDD files listed

D. No files listed, error occurs

Solution

1. Step 1: Understand the script actions

   The script renames syslog to syslog-YYYYMMDD (today's date), then creates a new empty syslog file.

2. Step 2: Predict the ls output

   After these steps, both /var/log/syslog (empty) and /var/log/syslog-YYYYMMDD exist, so ls lists both.

3. Final Answer:

   /var/log/syslog and /var/log/syslog-YYYYMMDD files listed -> Option C

4. Quick Check:

   mv + new empty file + ls = both files [OK]

Hint: Renaming then recreating file shows both in listing [OK]

Common Mistakes:

• Thinking syslog file is deleted
• Assuming mv copies instead of moves
• Ignoring the empty file creation with >

4. Identify the error in this Raspberry Pi log rotation script snippet:

logfile="/var/log/app.log"
backup="/var/log/app.log-$(date +%Y%m%d)"

mv $logfile $backup
> $logfile
find /var/log -type f -mtime 7 -delete

medium

A. The find command should use -mtime +7 to delete files older than 7 days

B. The mv command syntax is incorrect

C. The > $logfile line should be before mv command

D. The backup filename format is invalid

Solution

1. Step 1: Check the find command usage

   The find command uses -mtime 7 which matches files exactly 7 days old, not older than 7 days.

2. Step 2: Correct the find command

   To delete files older than 7 days, use -mtime +7 instead of -mtime 7.

3. Final Answer:

   The find command should use -mtime +7 to delete files older than 7 days -> Option A

4. Quick Check:

   find -mtime +7 deletes older files [OK]

Hint: Use + before days in -mtime to delete older files [OK]

Common Mistakes:

• Using -mtime 7 deletes only files exactly 7 days old
• Misplacing the > $logfile line
• Incorrect mv command syntax

5. You want to automate log rotation on your Raspberry Pi so that every day the current log file /var/log/myapp.log is renamed with the date, a new empty log is created, and logs older than 14 days are deleted. Which script snippet correctly performs this task?

hard

A. mv /var/log/myapp.log /var/log/myapp.log-$(date +%Y%m%d)
> /var/log/myapp.log
find /var/log -type f -name 'myapp.log-*' -mtime 14 -delete

B. mv /var/log/myapp.log /var/log/myapp.log-$(date +%Y%m%d)
rm /var/log/myapp.log
find /var/log -type f -mtime +14 -delete

C. backup="/var/log/myapp.log-$(date +%Y%m%d)"
cp /var/log/myapp.log $backup
> /var/log/myapp.log
find /var/log -type f -name 'myapp.log-*' -mtime 14 -delete

D. backup="/var/log/myapp.log-$(date +%Y%m%d)"
mv /var/log/myapp.log $backup
> /var/log/myapp.log
find /var/log -type f -name 'myapp.log-*' -mtime +14 -delete

Solution

1. Step 1: Rename current log and create new empty log

   backup="/var/log/myapp.log-$(date +%Y%m%d)" mv /var/log/myapp.log $backup > /var/log/myapp.log find /var/log -type f -name 'myapp.log-*' -mtime +14 -delete correctly moves the log file to a dated backup and creates a new empty log with >.

2. Step 2: Delete logs older than 14 days

   backup="/var/log/myapp.log-$(date +%Y%m%d)" mv /var/log/myapp.log $backup > /var/log/myapp.log find /var/log -type f -name 'myapp.log-*' -mtime +14 -delete uses find with -name 'myapp.log-*' and -mtime +14 to delete backups older than 14 days, which is correct.

3. Final Answer:

   backup="/var/log/myapp.log-$(date +%Y%m%d)" mv /var/log/myapp.log $backup > /var/log/myapp.log find /var/log -type f -name 'myapp.log-*' -mtime +14 -delete -> Option D

4. Quick Check:

   mv + new file + find -mtime +14 = correct rotation [OK]

Hint: Move log, recreate empty, delete backups older than 14 days [OK]

Common Mistakes:

• Using rm instead of recreating empty log
• Using -mtime 14 instead of +14 in find
• Copying instead of moving log file