Ubuntu find Command Safe Usage: Avoid Deletion Accidents

Safe find Usage - Avoid Deletion Accidents
Reading time: ~10 min Level: Intermediate

What You'll Learn

  • Basic find searches (by name, extension, modification date, size)
  • Safe deletion procedure (list first → verify count → delete)
  • Safe practices with xargs (-print0 / xargs -0)

💡 Quick Summary

Follow this order for deletions - it's non-negotiable:

  1. List first (don't delete)
  2. Verify count (stop if more than expected)
  3. Delete safely (use -print0 / xargs -0 when possible)

Table of Contents

  1. find Basics (Searching)
  2. Filtering by Date & Size
  3. Before Deletion: List & Count First
  4. Safe Deletion Methods
  5. Common Pitfalls
  6. Post-Deletion Verification

⚠️ Prerequisites

  • OS: Ubuntu
  • Shell: bash
  • Permissions: sudo when needed (for system directories)

1. find Basics (Searching)

1-1. Search by Name (Exact Match)

$ find . -name "error.log"

1-2. Search by Extension (e.g., .log)

$ find . -name "*.log"

1-3. Case-Insensitive Search

$ find . -iname "*.log"

1-4. Files Only / Directories Only

$ find . -type f -name "*.log"   # files only
$ find . -type d -name "cache"   # directories only

2. Filtering by Modification Date & Size

2-1. Files Modified Within Last 7 Days

$ find . -type f -mtime -7

2-2. Files Older Than 30 Days

$ find . -type f -mtime +30

2-3. Files Larger Than 100MB

$ find . -type f -size +100M

💡 Useful for finding "heavy files" during disk space investigations.

3. Before Deletion: List & Count First

3-1. List Files (Without Deleting)

Example: Find .log files under /var/log (use sudo if needed)

$ sudo find /var/log -type f -name "*.log"

3-2. Count Files (Stop If Too Many)

$ sudo find /var/log -type f -name "*.log" | wc -l

💡 If the count is higher than expected, your conditions are too broad. Add -mtime or -size to narrow down.

4. Safe Deletion Methods (Beginner Pattern)

Deletion can cause instant accidents, so it's best to use a fixed procedure.

4-1. First, Narrow Down (e.g., .log older than 30 days)

$ sudo find /var/log -type f -name "*.log" -mtime +30

4-2. Next, Verify Count

$ sudo find /var/log -type f -name "*.log" -mtime +30 | wc -l

4-3. If OK, Delete Safely

Use -print0 and xargs -0 to handle filenames with spaces safely.

$ sudo find /var/log -type f -name "*.log" -mtime +30 -print0 | sudo xargs -0 rm -f
  • -print0: Output null-delimited (safe for spaces/newlines)
  • xargs -0: Accept null-delimited input correctly

rm -f is powerful. Always follow the "list → count → delete" order.

Is -delete OK to Use? (Answer: Be Careful)

find ... -delete is simple but can cause instant accidents if conditions are wrong.

# Only use if you understand the risks
$ sudo find /tmp -type f -mtime +7 -delete

For beginners, master the -print0 | xargs -0 rm pattern first.

5. Common Pitfalls (Where Accidents Happen)

❌ Wrong Path (/ vs ./)

  • find / ... affects the entire system - be very careful
  • Always verify the target directory with pwd and ls first
$ pwd
$ ls -la

❌ Conditions Too Broad

Just *.log might match too many files. Add -mtime or -size to narrow down.

Example: Older than 30 days AND larger than 10MB

$ sudo find /var/log -type f -name "*.log" -mtime +30 -size +10M

❌ Filenames with Spaces/Newlines Break

This is THE reason to use -print0 / xargs -0.

6. Post-Deletion Verification

After deletion, verify disk usage:

$ df -h

🔗 Related Articles

📋 Test Environment

Commands tested on Ubuntu 24.04 LTS / bash 5.2.

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