fm-linux

Overview

• A C-language command-line tool for detecting file modifications.
• Designed for checking differences after software installation or patch application.

Features

• Fast & Lightweight: High-speed scanning of large directories with C implementation.
• Strict Change Detection: Accurate detection of content changes using MD5 hash.
• Flexible Target Specification: Supports arbitrary and multiple directories.
• Exclude Patterns: Exclude by partial match of subdirectory or file name.
• Colored Output: Color-coded display of changes (can be disabled with --no-color).

Required Libraries

• OpenSSL (libssl-dev or openssl-devel)
  • Compatible with OpenSSL 1.1.x / 3.0.x

Ubuntu/Debian

sudo apt-get install libssl-dev

CentOS/RHEL

sudo dnf install openssl-devel

Build

make

Or manually:

gcc -Wall -O2 -D_GNU_SOURCE -o fm fm.c -lssl -lcrypto
sudo cp -f ./build/fm /usr/local/bin/

Arguments

Required Options

Specify one of the following:

• --baseline, -B <directory(,directory...)>

  • Baseline creation mode. Records file information under the specified directories.
  • By default, saves to /tmp/fm_baseline.dat.
  • You can specify any path with --baseline-file.

• --check, -C <directory(,directory...)>

  • Change check mode. Detects changed, new, and deleted files by comparing with the baseline.
  • You can specify any baseline file with --baseline-file.

• --reset or -R

  • Deletes (resets) the baseline file.
  • You can specify any baseline file with --baseline-file.
  • By default, deletes /tmp/fm_baseline.dat.

Optional Options

• --exclude <pattern> or -e <pattern>
  • Exclude pattern (partial match). Can be specified as comma-separated or multiple times.
• --baseline-file, -b
  • Specify baseline file name.
• --no-color
  • Disable colored output.

Usage Examples

1. Create Baseline (file info before work)

fm -B /etc,/usr

2. Check for Changes

fm -C /etc,/usr

3. Reset Baseline

fm -R

Exclude Patterns

Use --exclude for partial match exclusion. Can be specified as comma-separated or multiple times.

fm -B / --exclude /tmp/,/var/log/
fm -C /usr,/etc --exclude /log/,/tmp/

• The following directories are automatically excluded:
  • /tmp/
  • /var/log/
  • /proc/
  • /sys/
  • /dev/

Colored Output

Color-coded display by default. Disable with --no-color.

Exit Codes

• 0: No changes
• 1: Error
• 2: Changes detected

Notes and Limitations

• Up to 8 baseline files can be specified. Any excess will be ignored with a warning.
• Exclude patterns use partial match. Multiple specifications and multiple times are allowed.
• If you specify --baseline-file (-b) or --exclude (-e) multiple times, only the last value is effective (overwritten).
• MD5 calculation is strict but increases processing time. May take time if there are many files.
• Files that cannot be read are automatically skipped.
• Compatible with OpenSSL 3.0 (uses EVP API).
• Colored output can be disabled with --no-color.

License

This project is licensed under the MIT License. See the LICENSE file for details.