diskc

Find what is filling your Linux disk, how fast it is growing, and which process is writing it.

diskc is a read-only, SRE-focused CLI that combines the usual df, df -i, du, find, lsof, ps, and /proc investigation into one workflow.

Quick Start

Build and run from source:

go build -o diskc ./cmd/diskc
./diskc

The default command scans /, samples growth for three seconds, and reports filesystem pressure, largest files/directories, growth rate, estimated time-to-full, and writable processes. Add --deleted to include deleted-open file detection.

diskc is read-only and does not require sudo or root privileges. Linux /proc permissions may limit process details for other users.

Example Output

$ ./diskc
Disk pressure: WARNING  92.4% used (38.0 GB free)
Inodes: 41.0% used  |  /
Trend: +2.4 GB/hour
Estimated filesystem full: ~35 minutes

Largest files
   74.8 GB  /var/log/payment/app.log  (log)  ↑ 18.2 MB/s  [1 writer(s)]
   42.1 GB  /tmp/upload-883120.bin   (temporary/cache)  ↑ 11.8 MB/s

Active writers
/var/log/payment/app.log
└─ PID 21819  payment-api
   ├─ exe      /opt/payment/bin/payment-api
   └─ service  payment.service

Potential issues
/var/log/payment/app.log
├─ rapid growth: 65.5 GB/hour
└─ filesystem full in ~35 minutes

Common Commands

Inspect a directory or filesystem:

./diskc /var
./diskc /var/log --top 50 --depth 6

Measure growth over a custom window:

./diskc /var --sample 5s

Inspect multiple filesystems explicitly:

./diskc / /data /backup --sample 5s

Discover physical filesystems automatically:

./diskc --all --sample 5s

Virtual filesystems such as /proc, /sys, tmpfs, and cgroups are excluded. Separate filesystem results are never mixed.

Watch continuously until Ctrl-C:

./diskc -watch
./diskc --watch --interval 5s /data

The default refresh interval is three seconds between refresh starts. If a scan takes longer, the next refresh starts immediately.

Find deleted-but-open files:

./diskc --deleted

Example:

Deleted but still open
   38.2 GB  /var/log/payment/app.log  ← payment-api (PID 21819)

JSON Output

./diskc /data --top 50 --sample 3s --deleted --json > disk-report.json

For multiple filesystems, JSON output is an array:

[
  {
    "filesystem": {
      "path": "/data",
      "used_percent": 92.4,
      "inode_percent": 41
    },
    "files": [
      {
        "path": "/data/events.log",
        "size_bytes": 13314398617,
        "kind": "log",
        "growth_bytes_per_second": 4299161,
        "writers": [{"pid": 21819, "process": "payment-api", "exe": "/opt/payment/bin/payment-api", "uid": "1001"}]
      }
    ]
  }
]

With --watch --json, each refresh is emitted as a separate JSON document without terminal-control sequences.

Installation

Requires Go 1.22 or newer:

go run ./cmd/diskc
go build -o diskc ./cmd/diskc

The module is organized for Homebrew. After publishing a tap:

brew tap your-org/diskc
brew install diskc

The formula builds ./cmd/diskc and installs the resulting diskc binary.

Flags

--top N              number of large files (default: 20)
--depth N            maximum directory depth (default: 4)
--sample DURATION    measure growth (default: 3s; use 0 to disable)
--deleted            include deleted files held open by processes
--json               emit machine-readable JSON
--all                inspect all mounted physical filesystems
--watch              refresh continuously until interrupted
--interval DURATION  watch refresh interval (default: 3s)

Disclaimer

Parts of this project, including source code, documentation, examples, and configuration, may be generated or assisted by artificial intelligence. The project is provided on an “AS IS” and “AS AVAILABLE” basis, without warranties of any kind.

Use diskc at your own risk. The authors, maintainers, contributors, and distributors are not liable for any damage, data loss, corruption, downtime, outage, security incident, or other loss arising from the use of all or any part of this project. Review, test, and validate the code and its output before using it in production.

Contributing

The project uses only the Go standard library. Linux builds use filesystem statistics and /proc metadata.

Run formatting, tests, static analysis, and builds with:

gofmt -w cmd internal
go test ./...
go vet ./...
go build ./cmd/diskc
GOOS=linux GOARCH=amd64 go build -o diskc-linux ./cmd/diskc

Pull requests and issues are welcome at github.com/diskc-cli/diskc.