mc head
Syntax
The mc head
command displays the first n
lines of an object,
where n
is an argument specified to the command.
mc head
does not perform any transformation or formatting of object
contents to facilitate readability. You can also use mc head
against
the local filesystem to produce similar results to the head
commandline
tool.
The following command returns the first 10 lines of an object in the
mydata
bucket on the myminio
MinIO deployment:
mc head myminio/mydata/myobject.txt
The command has the following syntax:
mc [GLOBALFLAGS] head \
[--lines int] \
[--rewind "string"] \
[--version-id "string"] \
[--encrypt-key "string"] \
ALIAS [ALIAS ...]
Brackets
[]
indicate optional parameters.Parameters sharing a line are mutually dependent.
Parameters separated using the pipe
|
operator are mutually exclusive.
Copy the example to a text editor and modify as-needed before running the command in the terminal/shell.
Parameters
- ALIAS
Required The object or objects to print.
For an object on MinIO, specify the alias and the full path to that object (e.g. bucket and path to object). For example:
mc head play/mybucket/object.txt
You can specify multiple objects on the same or different MinIO deployments. For example:
mc head ~/mydata/object.txt myminio/mydata/object.txt
For an object on a local filesystem, specify the full path to that object. For example:
mc head ~/mydata/object.txt
- --encrypt-key
Optional Encrypt or decrypt objects using server-side encryption with client-specified keys. Specify key-value pairs as
KEY=VALUE
.Each
KEY
represents a bucket or object.- Each
VALUE
represents the data key to use for encrypting object(s).
- Each
Enclose the entire list of key-value pairs passed to
--encrypt-key
in double quotes"
.--encrypt-key
can use theMC_ENCRYPT_KEY
environment variable for retrieving a list of encryption key-value pairs as an alternative to specifying them on the command line.
- --rewind
- Optional
Directs
mc head
to operate only on the object version(s) that existed at specified point-in-time.To rewind to a specific date in the past, specify the date as an ISO8601-formatted timestamp. For example:
--rewind "2020.03.24T10:00"
.To rewind a duration in time, specify the duration as a string in
#d#hh#mm#ss
format. For example:--rewind "1d2hh3mm4ss"
.
--rewind
requires that the specifiedALIAS
be an S3-compatible service that supports Bucket Versioning. For MinIO deployments, usemc version
to enable or disable bucket versioning.
- --version-id, vid
Optional Directs
mc head
to operate only on the specified object version.--version-id
requires that the specifiedALIAS
be an S3-compatible service that supports Bucket Versioning. For MinIO deployments, usemc version
to enable or disable bucket versioning.
Global Flags
This command supports any of the global flags.
Examples
View Partial Contents of an Object
Use mc head
to return the first 10 lines of an object:
mc head ALIAS/PATH
View Partial Contents of an Object at a Point in Time
Use mc head --rewind
to return the first 10 lines of the
object at a specific point-in-time in the past:
mc head ALIAS/PATH --rewind DURATION
Replace
PATH
with the path to the object on the S3-compatible host.Replace
DURATION
with the point-in-time in the past at which the command returns the object. For example, specify30d
to return the version of the object 30 days prior to the current date.
Requires Versioning
mc head
requires bucket versioning to
use this feature. Use mc version
to enable versioning on a bucket.
View Partial Contents of an Object with Specific Version
Use mc head --version-id
to return the first 10 lines of the
object at a specific point-in-time in the past:
mc head ALIAS/PATH --version-id VERSION
Replace
PATH
with the path to the object on the S3-compatible host.Replace
VERSION
with the version of the object. For example, specify30d
to return the version of the object 30 days prior to the current date.
Requires Versioning
mc head
requires bucket versioning to
use this feature. Use mc version
to enable versioning on a bucket.
Behavior
S3 Compatibility
The mc commandline tool is built for compatibility with the AWS S3 API and is tested with MinIO and AWS S3 for expected functionality and behavior.
MinIO provides no guarantees for other S3-compatible services, as their S3 API implementation is unknown and therefore unsupported. While mc commands may work as documented, any such usage is at your own risk.