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Parallel S3 and local filesystem execution tool.
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doc Update timing on demo recording May 17, 2017

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This is a parallel S3 and local filesystem execution tool.




You'll need Go 1.8+ to install s5cmd.

go get -u

This will install s5cmd in your $GOPATH/bin directory.

Using Homebrew:

brew tap peak/s5cmd
brew install s5cmd

Shell Auto-Completion

Bash and zsh shell completion is supported, utilizing posener/complete. Tool and subcommand parameters, local files/dirs, as well as remote (S3) buckets and objects are supported.

To enable auto-completion, run:

s5cmd -cmp-install

This will add a few lines (depending on configuration) to your .bashrc or .zshrc file. After installation, run source .bashrc (or restart your shell) to activate the changes.

Note: Auto-completion always works with AWS Endpoint, -endpoint-url does not override it's behaviour.


To utilize shell autocompletion, use the <tab> key on the shell CLI. If there is more than one match, nothing will happen until a second <tab> is hit, which then will show options. Examples:

s5cmd <tab> # This is going to list commands and general parameters
s5cmd -n<tab> # This will autocomplete to "s5cmd -numworkers"
s5cmd -numworkers <tab><tab> # This will recommend some values for numworkers
s5cmd ls <tab><tab> # This will recommend options for the "ls" command or an "s3://" prefix
s5cmd ls s3://<tab><tab> # This will get a bucket list from S3
s5cmd ls s3://my-buck<tab> # This will complete this to "s3://my-bucket"

# These commands below will recommend up to 20 S3 objects or complete if there's only one match:
s5cmd ls s3://my-bucket/<tab><tab>
s5cmd ls s3://my-bucket/my-prefix/<tab><tab>
s5cmd ls s3://my-bucket/my-prefix/some-object<tab>


$ ./s5cmd

Usage: s5cmd [OPTION]... [COMMAND [PARAMS...]]

    	Install shell completion
    	Uninstall shell completion
  -ds int
    	Multipart chunk size in MB for downloads (default 50)
  -dw int
    	Download concurrency (single file) (default 5)
  -endpoint-url string
    	Override default URL with the given one
  -f string
    	Commands-file or - for stdin
    	Initialize gops agent
    	Install completion for s5cmd command
    	Don't verify SSL certificates
  -numworkers int
    	Number of worker goroutines. Negative numbers mean multiples of the CPU core count. (default 256)
  -r int
    	Retry S3 operations N times before failing (default 10)
    	Always print stats
    	Uninstall completion for s5cmd command
  -us int
    	Multipart chunk size in MB for uploads (default 50)
  -uw int
    	Upload concurrency (single file) (default 5)
    	Prints current version
    	Verbose output
  -y	Don't prompt user for typing 'yes'

    !, cp, du, exit, get, ls, mv, rm

To get help on a specific command, run "s5cmd <command> -h"

Commands File

The most powerful feature of s5cmd is the commands file. Thousands of S3 and filesystem commands are declared in a file (or simply piped in from another process) and they are executed using multiple parallel workers. Since only one program is launched, thousands of unnecessary fork-exec calls are avoided. This way S3 execution times can reach a few thousand operations per second.

See also: Nested Commands

Single command invocation

Single commands are also supported with the s5cmd [command [params]] syntax.

Supported commands

There are three main commands: cp, mv and rm. Arguments can be either S3 urls, S3 wildcards, local file/directory references or local glob patterns.

  • Copy, Download or Upload: cp [options] [src] [dst]
    • Note, the directory hierarchy will be flattened by default. Pass --parents to preserve the dir structure
  • Move, Download or Upload and then delete: mv [options] [src] [dst]
    • Note, the directory hierarchy will be flattened by default. Pass --parents to preserve the dir structure
  • Delete: rm [src]
  • Count objects and determine total size: du [src]
  • Arbitrary shell-execute - ! commands...
  • Exit - exit [exitcode] (see Exit Code)

Command options

  • S3 urls should be in the format s3://bucket/key
  • cp and mv commands accept the -n (no-clobber) option to prevent overwriting existing files or objects, -s option to match source-destination file sizes and skip upload if sizes are equal, and -u option to match source-destination last modification times and skip upload if destination is newer or same. If these options are combined, overwrite is skipped only if all of the specified conditions are met.
  • Uploading cp and mv commands accept the -rr and -ia options to store objects in reduced-redundancy and infrequent-access modes respectively.
  • Batch cp and mv commands also accept the --parents option to create the dir structure in destination. Dir structure is created from the first wildcard onwards.
  • Batch local-to-local cp and mv commands also accept the -R option for recursive operation.
  • The ls command accepts the -e option to show ETags in listing.
  • The du command only takes S3 arguments (prefix or wildcard)
  • ls and du commands both accept the -H option to show human-readable object sizes.
  • du command also accepts the -g option to group by storage class.

Command examples

cp s3://from-bucket/from-key s3://to-bucket/[to-key] # Copy object in S3 
mv s3://from-bucket/from-key s3://to-bucket/[to-key] # Move object in S3
rm s3://del-bucket/del-key # Delete S3 object
cp /path/to/src/file /path/to/dest[/] # Copy local file
mv /path/to/src/file /path/to/dest[/] # Move local file
cp s3://from-bucket/from-key /path/to/dest[/] # Download from S3
rm /path/to/del # Delete local file or (empty) directory
ls # List buckets
ls s3://bucket[/prefix] # List objects in bucket
cp /path/to/src s3://to-bucket/to-key[/] # Upload to S3
cp /path/to/src/dir/ s3://to-bucket/to-prefix/ # Upload directory to S3
cp /path/to/src/*.go s3://to-bucket/to-prefix/ # Upload glob to S3

Wild operations

Multiple-level wildcards are supported in S3 operations. This is achieved by listing all S3 objects with the prefix up to the first wildcard, then filtering the results in-memory. ie. For batch-downloads, first a ls call is made, the results are then converted to separate commands and executed in parallel.

Batch API is used deleting multiple S3 objects, so up to 1000 S3 objects can be deleted with a single call.

Wild operation examples

ls s3://bucket/prefix/*/file*gz # Wild-list objects in bucket
cp s3://from-bucket/prefix/*/file*gz /path/to/dest/ # Wild-download from S3
mv s3://from-bucket/prefix/*/file*gz /path/to/dest/ # Wild-download from S3, followed by delete
rm s3://from-bucket/prefix/*/file*gz # Wild-delete S3 objects (Batch-API)


  • Comments start with a space followed by #, as in " # This is a comment"
  • Empty lines are also ok
  • -numworkers -1 means use runtime.NumCPU goroutines. -2 means 2*runtime.NumCPU and so on.
  • The S3 throttling error SlowDown is exponentially retried. "Retryable operations" as specified by the AWS SDK (currently RequestError and RequestError) are retried by the SDK.

Nested Commands (Basic)

Success and fail commands can be specified with && and || operators. As the parser is pretty simple, multiple-level nested commands (doing something based on a result of a result) are not supported.

If you want to move an object between s3 buckets and then delete a local file if successful, you can do this:

mv s3://source-bkt/key s3://dest-bkt/key && rm /path/to/key

This is also valid:

mv a b/ || ! touch could-not-move # This is a comment

This as well:

! touch a && ! touch a-touched || ! touch a-couldnotbetouched

S3 Credentials

S3 credentials can be provided in a variety of ways.

Full environment variables

Provide full S3 credentials with the environment variables:


Credentials file

Use the $HOME/.aws/credentials file:

aws_access_key_id = YOURKEY
aws_secret_access_key = ohnosecret
region = us-east-1

Then run s5cmd:

./s5cmd ls

To use a different profile, set the AWS_PROFILE env var. For more options, see the AWS SDK Configuration page.


The general output is in the format:

DATE TIME Short-Msg Detailed-Msg
  • Trivial messages start with #, like number of workers or exit code and statistics
  • +OK for successful operations: +OK "! touch touch-this-file"
  • -ERR for failed operations: -ERR "! touche": executable file not found in $PATH
  • ?ErrorCode for AWS-related errors, which will be retried (?SlowDown, ?InternalError, etc)

Item output (used in ls) is slightly different: DATE TIME fields are omitted, and the short-msg is a single + character.

Shell output (used in !) does not modify the executed command's output. Both stdout and stderr are mirrored.

Exit Code

If failed jobs are present, process exits with code 127. This can be overridden with the command exit, though in that case finishing the job list is not guaranteed.

Environment Variables

Set S5CMD_GOPS to always enable the gops agent.

Supported platforms

  • s5cmd is tested on Linux and macOS. Should work on Windows, however not tested as of release time.
  • Go 1.8 and up is supported.
  • Use in production environments is OK. (it works fine for us -- but as always with trying out new tools, proceed with caution)
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