Bash Script to Delete Files Older Than N Days

Use the command find /path/to/files -type f -mtime +n -exec rm {} \; in a Bash script to delete files older than n days.

Examples

Inputn=7, directory=/tmp/test

OutputDeletes all files in /tmp/test older than 7 days.

Inputn=0, directory=/var/log

OutputDeletes all files older than today (i.e., files modified before current day) in /var/log.

Inputn=30, directory=/home/user/downloads

OutputDeletes files older than 30 days in /home/user/downloads.

How to Think About It

To delete files older than n days, you look for files with modification times older than n days using find and then remove them. The -mtime +n option finds files modified more than n days ago. Then you delete those files safely.

Algorithm

1

Get the directory path and number of days (n) as input.

2

Use the <code>find</code> command to locate files older than n days in the directory.

3

For each found file, delete it using <code>rm</code>.

4

Print a message confirming deletion or errors.

Code

bash

#!/bin/bash

# Directory to clean
DIR="$1"
# Number of days
DAYS="$2"

if [[ -z "$DIR" || -z "$DAYS" ]]; then
  echo "Usage: $0 <directory> <days>"
  exit 1
fi

# Find and delete files older than DAYS
find "$DIR" -type f -mtime +$DAYS -exec rm {} \;

echo "Deleted files older than $DAYS days in $DIR."

Output

Deleted files older than 7 days in /tmp/test.

Dry Run

Let's trace deleting files older than 7 days in /tmp/test.

1

Input parameters

DIR=/tmp/test, DAYS=7

2

Find command runs

find /tmp/test -type f -mtime +7 -exec rm {} \;

3

Files deleted

All files older than 7 days in /tmp/test are removed.

File Path	Modified Days Ago	Action
/tmp/test/file1.txt	10	Deleted
/tmp/test/file2.log	8	Deleted
/tmp/test/file3.tmp	5	Kept

Why This Works

Step 1: Finding files older than n days

The find command with -mtime +n selects files modified more than n days ago.

Step 2: Deleting files safely

The -exec rm {} \; part runs rm on each found file to delete it.

Step 3: Using variables for flexibility

Passing directory and days as variables makes the script reusable for any folder and time period.

Alternative Approaches

Using find with -delete option

bash

#!/bin/bash
DIR="$1"
DAYS="$2"

if [[ -z "$DIR" || -z "$DAYS" ]]; then
  echo "Usage: $0 <directory> <days>"
  exit 1
fi

find "$DIR" -type f -mtime +$DAYS -delete

echo "Deleted files older than $DAYS days in $DIR."

This method is simpler and faster but <code>-delete</code> is not supported on all systems.

Using find with xargs

bash

#!/bin/bash
DIR="$1"
DAYS="$2"

if [[ -z "$DIR" || -z "$DAYS" ]]; then
  echo "Usage: $0 <directory> <days>"
  exit 1
fi

find "$DIR" -type f -mtime +$DAYS -print0 | xargs -0 rm

echo "Deleted files older than $DAYS days in $DIR."

Using <code>xargs</code> can be more efficient for many files but requires careful handling of filenames with spaces.

Complexity: O(m) time, O(1) space

Time Complexity

The script runs find which scans all files in the directory tree, so time depends linearly on the number of files (m).

Space Complexity

The script uses constant extra memory since it deletes files in place without storing lists.

Which Approach is Fastest?

Using -delete is fastest as it avoids spawning rm for each file, but -exec rm is more portable.

Approach	Time	Space	Best For
find with -exec rm	O(m)	O(1)	Portability and safety
find with -delete	O(m)	O(1)	Speed on supported systems
find with xargs rm	O(m)	O(1)	Efficiency with many files