knife xargs

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Use the knife xargs subcommand to take patterns from standard input, download as JSON, run a command against the downloaded JSON, and then upload any changes.

Syntax

This subcommand has the following syntax:

$ knife xargs [PATTERN...] (options)

Options

Note

Review the list of common options available to this (and all) knife subcommands and plugins.

This subcommand has the following options:

-0
Show a NULL character (\0) instead of white space as the separator. Default: false.
--chef-repo-path PATH
The path to the chef-repo. This setting will override the default path to the chef-repo. Default: same value as specified by chef_repo_path in client.rb.
--concurrency
The number of allowed concurrent connections. Default: 10.
--[no-]diff
Show a diff when a file changes. Default: --diff.
--dry-run

Prevent changes from being uploaded to the Chef server. Default: false.

New in Chef Client 12.0.

--[no-]force
Force the upload of files even if they haven’t been changed. Default: --no-force.
-I REPLACE_STRING, --replace REPLACE_STRING
Define a string that is to be used to replace all occurrences of a file name. Default: nil.
-J REPLACE_STRING, --replace-first REPLACE_STRING
Define a string that is to be used to replace the first occurrence of a file name. Default: nil.
--local
Build or execute a command line against a local file. Set to false to build or execute against a remote file. Default: false.
-n MAX_ARGS, --max-args MAX_ARGS
The maximum number of arguments per command line. Default: nil.
-p [PATTERN...], --pattern [PATTERN...]
One (or more) patterns for a command line. If this option is not specified, a list of patterns may be expected on standard input. Default: nil.
--repo-mode MODE
The layout of the local chef-repo. Possible values: static, everything, or hosted_everything. Use static for just roles, environments, cookbooks, and data bags. By default, everything and hosted_everything are dynamically selected depending on the server type. Default value: default.
-s LENGTH, --max-chars LENGTH
The maximum size (in characters) for a command line. Default: nil.
-t
Run the print command on the command line. Default: nil.

Note

See knife.rb for more information about how to add certain knife options as settings in the knife.rb file.

Examples

The following examples show how to use this knife subcommand:

Find, and then replace data

The following example will go through all nodes on the server, and then replace the word foobar with baz:

$ knife xargs --pattern /nodes/* "perl -i -pe 's/foobar/baz'"

Use output of knife list and Perl

The following examples show various ways of listing all nodes on the server, and then using Perl to replace grantmc with gmc:

$ knife list 'nodes/*' | knife xargs "perl -i -pe 's/grantmc/gmc'"

or without quotes and the backslash escaped:

$ knife list /nodes/\* | knife xargs "perl -i -pe 's/grantmc/gmc'"

or by using the --pattern option:

$ knife xargs --pattern '/nodes.*' "perl -i -pe 's/grantmc/gmc'"

View security groups data

The following example shows how to display the content of all groups on the server:

$ knife xargs --pattern '/groups/*' cat

and will return something like:

{
  "name": "4bd14db60aasdfb10f525400cdde21",
  "users": [
    "grantmc"
  ]
}{
  "name": "62c4e268e15fasdasc525400cd944b",
  "users": [
    "robertf"
  ]
}{
  "name": "admins",
  "users": [
    "grantmc",
    "robertf"
  ]
}{
  "name": "billing-admins",
  "users": [
    "dtek"
  ]
}{
  "name": "clients",
  "clients": [
    "12345",
    "67890",
  ]
}{
  "name": "users",
  "users": [
    "grantmc"
    "robertf"
    "dtek"
  ],
  "groups": [
    "4bd14db60aasdfb10f525400cdde21",
    "62c4e268e15fasdasc525400cd944b"
  ]
}