7 Powerful Ways to Use the Linux find Command (Including Interview Tips)

The find command is an essential tool for Linux system administrators and backend developers, frequently appearing in technical interviews. A typical interview question asks how to delete log files in a logs directory that haven’t been accessed for over a year.

Find by name or regular expression

Search for a specific file name: find . -name test.txt Search for all PDF books using a pattern: find ./yang/books -name "*.pdf" It is advisable to limit the search to regular files with -type f for clarity:

find ./yang/books -type f -name "*.pdf"

Find different file types

Search for directories: find . -type d -name "yang*" Search for symbolic links:

find . -type l -name "yang*"

Find by timestamps

atime : last access time.

mtime : last modification time of file contents.

ctime : last change time of file metadata (owner, permissions, etc.).

Find files not accessed for more than 365 days: find . -type f -atime +365 Find files whose modification time is exactly five days ago (no + sign): find . -type f -mtime 5 Find files with change time between 5 and 10 days ago:

find . -type f -ctime +5 -ctime -10

Find by size

The -size option lets you specify units: b (512‑byte blocks, default), c (bytes), w (two‑byte words), k (KB), M (MB), G (GB). Use + for “greater than” and - for “less than”. Example: find files between 10 MB and 1 GB:

find . -type f -size +10M -size -1G

Find by permissions

Search for files with specific permission bits using -perm: find . -type f -perm 777 This returns files that are readable, writable, and executable by owner, group, and others.

Find by ownership

Use -user to locate files owned by a particular user:

find . -type f -user yang

Execute a command on matched files

The -exec action runs a specified command for each file found. For the interview problem, combine the timestamp filter with -exec rm -rf {} to delete old log files: find . -type f -atime +365 -exec rm -rf {} \; Note that {} is a placeholder for each matched file; without it, the command would act on all files in the directory.

Example showing the effect of using or omitting the placeholder:

find . -type f -atime +5 -exec ls {} \;

find . -type f -atime +5 -exec ls \;

Summary

After learning these seven practical uses of find, the interview question becomes straightforward. The final solution to delete files not accessed for over a year is:

find . -type f -atime +365 -exec rm -rf {} \;