Purpose: e4defrag is an online defragmenter for extent based files on ext4 filesystems.
Targets: It accepts a regular file, directory, or device mounted as ext4; a directory target covers its files.
Defragmentation: It aims to give targeted files more contiguous blocks, which the manual says improves file access speed.
Fragmentation check: The -c option reports current and ideal fragmentation counts and a fragmentation score without defragmenting the target.
Verbose output: The -v option prints error messages and each file’s fragmentation count before and after defragmentation.
Supported filesystem: The source checks for ext4 and reports an error when the filesystem is not ext4.
Unsupported files: The manual says e4defrag does not support swap files, files in lost+found, or files allocated in indirect blocks.
Other mount points: When given a device or mount point, it does not defragment files belonging to another device’s mount point.
Free space: Fragmented or insufficient filesystem free space can prevent e4defrag from improving a file’s fragmentation.
Use while active: The manual says it is safe to run on a file while another application uses it, though shared memory and disk bandwidth can slow both.
Permissions: Non-privileged users can run it on their own files, but the fragmentation score is not printed for -c runs unless run as root.
Project: The maker’s README describes e2fsprogs as second extended filesystem management programs and says it supplies instructions for building and installing them.
Support: The project README directs bug reports for its programs to Ted Ts’o by email.
Authors: The e4defrag source credits Akira Fujita and Takashi Sato as authors.
Price from: Free

Where it ranks on Freedom251

Best Disk Defragmentation Software in 2026#5 of 22

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Sources

man7.org/linux/man-pages/man8/e4defrag.8.html· checked 4 Oct 2026
github.com/tytso/e2fsprogs/blob/master/misc/e4defr· checked 4 Oct 2026
github.com/tytso/e2fsprogs/blob/master/README· checked 4 Oct 2026