Eval Operations#

This page documents all eval operations.

!eval#

Evaluate environment variables in a document

The !eval operation expands environment variables in the document. Variables are referenced using $varName syntax and are replaced with values from the evaluation environment.

Child: Document with $variable references

Examples:

1. ```tony name: !eval "$USER"

   
   2. ```tony
   path: !eval "/home/$USER/config"

See also: !os_env, !file

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!exec#

Execute a shell command and capture output

The !exec operation executes a shell command and captures its stdout. The child must be a string containing the command to execute. The command is run with 'sh -c'.

Child: String containing shell command

Examples:

1. ```tony date: !exec "date -u +%Y-%m-%d"

   
   2. ```tony
   hostname: !exec "hostname"

See also: !file, !script

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!file#

Load content from a file or URL

The !file operation loads content from a local file path or HTTP/HTTPS URL. The child must be a string containing the path or URL. The loaded content is parsed as Tony format.

Child: String containing file path or URL

Examples:

1. ```tony config: !file "/etc/config.tony"

   
   2. ```tony
   data: !file "https://example.com/data.tony"

See also: !exec, !eval

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!os_env#

Get value from OS environment variable

The !os_env operation retrieves the value of an OS environment variable. The child must be a string containing the environment variable name.

Child: String containing environment variable name

Examples:

1. ```tony home: !os_env "HOME"

   
   2. ```tony
   path: !os_env "PATH"

See also: !eval

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!to_int#

Convert a value to an integer

The !to_int operation converts its child value to an integer. The child must be a string representation of a number.

Child: String value to convert

Examples:

1. ```tony version: !to_int "123"

   
   **See also:** [`!to_string`](./eval.md#to_string), [`!to_value`](./eval.md#to_value)
   
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   ## `!to_string`
   
   **Convert a value to a string**
   
   The !to_string operation converts its child value to a string representation.
   
   **Child:** Value to convert
   
   **Examples:**
   
   1. ```tony
   version_str: !to_string 123

See also: !to_int, !to_value

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