Searching and filtering data efficiently is a core skill for every Linux user. This is Part 3 of our Linux commands series, where we focus on powerful search utilities like grep, find, and locate. These commands are widely used by system administrators, DevOps engineers, developers, and anyone working with large log files or file systems.
Commonly Used Commands
| Command | Description |
|---|---|
grep "word" <file> | Search for a word in a file |
grep -n "word" <file> | Search and display line numbers |
grep -c "word" <file> | Count the number of matches |
grep -i "word" <file> | Case-insensitive search |
grep "word" file1 file2 | Search across multiple files |
grep -l "word" * | List filenames containing the word |
grep -e "pattern1" -e "pattern2" <file> | Search for multiple patterns |
find . -name "filename" | Find a file in the current directory |
find /path -name "filename" | Find a file in a specific directory |
find . -type f -name "*.txt" | Find all .txt files |
find . -type d -name "folder" | Find a directory by name |
find . -perm 777 | Find files with 777 permissions |
find . ! -perm 777 | Find files without 777 permissions |
find . -user <username> | Find files owned by a user |
find . -group <groupname> | Find files owned by a group |
find . -empty | Find empty files and directories |
find . -mtime 10 | Find files modified 10 days ago |
find . -size 1K | Find files of size 1 KB |
find . -size +50M | Find files larger than 50 MB |
locate filename | Find files using the system database |
Detailed Examples
Sample Folder Structure
demo/ ├── file1.txt ├── file2.txt (777 permissions) ├── empty.txt ├── one_kb.bin (1 KB file) ├── folder1/ │ └── nested.txt └── folder2/
file1.txt
Hello World This is a test Word appears here Another word line
file2.txt
word is case sensitive Another Test line HELLO WORD
empty.txt
# empty file
folder1/nested.txt
# empty file
one_kb.bin
# binary file of size 1024 bytes
1. grep – Text Searching
# Search for a word grep "word" file1.txt Word appears here Another word line
# Show line numbers grep -n "word" file1.txt 3:Word appears here 4:Another word line
# Count matches grep -c "word" file1.txt 2
# Case-insensitive search grep -i "word" file2.txt word is case sensitive HELLO WORD
# Search in multiple files grep "word" file1.txt file2.txt file1.txt:Word appears here file1.txt:Another word line file2.txt:word is case sensitive
# List files containing the word grep -l "word" * file1.txt file2.txt
# Search multiple patterns grep -e "Hello" -e "Another" file1.txt Hello World Another word line
The grep command searches text for patterns. Common options include:
-i– Ignore case-n– Show line numbers-c– Count matches-l– Display filenames only-e– Match multiple patterns
2. find – File and Directory Search
# Find a file find . -name "file1.txt" ./file1.txt
# Find files in a specific directory find ./folder1 -name "nested.txt" ./folder1/nested.txt
# Find all text files find . -type f -name "*.txt" ./file1.txt ./file2.txt ./empty.txt ./folder1/nested.txt
# Find directories find . -type d -name "folder1" ./folder1
# Find files with 777 permissions find . -perm 777 ./file2.txt
# Find empty files and directories find . -empty ./empty.txt ./folder1/nested.txt
The find command is extremely powerful and allows you to search files based on name, type, permissions, ownership, size, and modification time.
3. locate – Fast Database Search
# Update database and locate file sudo updatedb locate file1.txt /home/user/demo/file1.txt
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