S3cmd

GitHub. s6cmd is a Go CLI for Amazon S3 using aws-sdk-go-v2, inspired by s3cmd. Supports ls, put, get, cp, sync, tree, mb, rm, stat. Actively under development. MIT License. Per GitHub (LinPr/s6cmd) (2025-09-02).

Releases · s3tools/s3cmd. Official s3cmd repo. v2.4.0 changelog: added versioning, tagging, retention, legal hold, ownership, block public access, CloudFront invalidation, keep-dirs, max-retries, FIPS. Fixed batch delete, md5 FIPS, NextMarker, sync dry-run, Cloudflare R2, unicode, whitespace delete, mime type issues. Per GitHub (s3tools/s3cmd) (2018-07-15).

s3cmd sync re-reads and re-hashes every file on each run instead of caching state. It computes MD5 checksums for the full file set on every invocation rather than relying on a local index, which is the underlying reason it's consistently the slowest of the S3 CLI tools on large trees. Tertiary source, no stronger corroboration found. Per Search Results: Simon Josefsson — Backup of S3 Objects Using rsnapshot.

On bulk transfers, s5cmd substantially outperforms s3cmd — roughly 32x faster uploads and ~50x faster downloads on a 40Gbps link (85 MB/s vs ~4.3 GB/s). s3cmd is described as functionally comprehensive but performance-mediocre at large scale; two independent Chinese-language technical write-ups reach the same ordering. Tertiary sources. Per S3命令行工具：s3cmd与s5cmd的实用指南 and s5cmd, s3cmd, rclone 上传文件到S3中的速度比较.

s4cmd positions itself as a multi-thread, multi-connection fork with s3cmd-compatible syntax, built on boto3, aimed at large-file (5GB+ chunked) and scheduled-sync workloads — but it drops feature completeness (no CloudFront support). Tertiary source. Per s3cmd Too Slow for Big Files? s4cmd Multi-Thread S3 2x Faster. Sources: GitHub (LinPr/s6cmd) · GitHub (s3tools/s3cmd)