open-consul/website/source/docs/commands/kv/put.html.markdown.erb

---
layout: "docs"
page_title: "Commands: KV Put"
sidebar_current: "docs-commands-kv-put"
---

# Consul KV Put

Command: `consul kv put`

The `kv put` command writes the data to the given path in the KV store.

## Usage

Usage: `consul kv put [options] KEY [DATA]`

#### API Options

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<%= partial "docs/commands/http_api_options_server" %>

#### KV Put Options

* `-acquire` - Obtain a lock on the key. If the key does not exist, this
  operation will create the key and obtain the lock. The session must already
  exist and be specified via the -session flag. The default value is false.

* `-base64` - Treat the data as base 64 encoded. The default value is false.

* `-cas` - Perform a Check-And-Set operation. Specifying this value also
  requires the -modify-index flag to be set. The default value is false.

* `-flags=<int>` - Unsigned integer value to assign to this KV pair. This
  value is not read by Consul, so clients can use this value however makes sense
  for their use case. The default value is 0 (no flags).

* `-modify-index=<int>` - Unsigned integer representing the ModifyIndex of the
  key. This is used in combination with the -cas flag.

* `-release` - Forfeit the lock on the key at the given path. This requires the
  -session flag to be set. The key must be held by the session in order to be
  unlocked. The default value is false.

* `-session=<string>` - User-defined identifier for this session as a string.
  This is commonly used with the -acquire and -release operations to build
  robust locking, but it can be set on any key. The default value is empty (no
  session).

## Examples

To insert a value of "5" for the key named "redis/config/connections" in the
KV store:

```
$ consul kv put redis/config/connections 5
Success! Data written to: redis/config/connections
```

If no data is specified, the key will be created with empty data:

```
$ consul kv put redis/config/connections
Success! Data written to: redis/config/connections
```

If the `-base64` flag is set, the data will be decoded before writing:

```
$ consul kv put -base64 foo/encoded aGVsbG8gd29ybGQK
Success! Data written to: foo/encoded
```

!> **Be careful when overwriting data!** The above operation would overwrite
the value at the key to the empty value.

For longer or sensitive values, it is possible to read from a file by prefixing
with the `@` symbol:

```
$ consul kv put redis/config/password @password.txt
Success! Data written to: redis/config/connections
```

Or read values from stdin by specifying the `-` symbol:

```
$ echo "5" | consul kv put redis/config/password -
Success! Data written to: redis/config/connections

$ consul kv put redis/config/password -
5
<CTRL+D>
Success! Data written to: redis/config/connections
```

~> For secret and sensitive values, you should consider using a secret
management solution like **[HashiCorp's Vault](https://www.vaultproject.io/)**.
While it is possible to secure values in Consul's KV store, Vault provides a
more robust interface for secret management.

To only update a key if it has not been modified since a given index, specify
the `-cas` and `-modify-index` flags:

```
$ consul kv get -detailed redis/config/connections | grep ModifyIndex
ModifyIndex      456

$ consul kv put -cas -modify-index=123 redis/config/connections 10
Error! Did not write to redis/config/connections: CAS failed

$ consul kv put -cas -modify-index=456 redis/config/connections 10
Success! Data written to: redis/config/connections
```

To specify flags on the key, use the `-flags` option. These flags are completely
controlled by the user:

```
$ consul kv put -flags=42 redis/config/password s3cr3t
Success! Data written to: redis/config/password
```

To create or tune a lock, use the `-acquire` and `-session` flags. The session must already exist (this command will not create it or manage it):

```
$ consul kv put -acquire -session=abc123 redis/lock/update
Success! Lock acquired on: redis/lock/update
```

When you are finished, release the lock:

```
$ consul kv put -release -session=acb123 redis/lock/update
Success! Lock released on: redis/lock/update
```

~> **Warning!** If you are trying to build a locking mechanism with these
low-level primitives, you may want to look at the [<tt>consul
lock</tt>](/docs/commands/lock.html) command. It provides higher-level
functionality without exposing the internal APIs of Consul.