mirror of
https://github.com/mikefarah/yq.git
synced 2026-06-29 16:41:45 +00:00
77 lines
2.1 KiB
Markdown
77 lines
2.1 KiB
Markdown
# System Operators
|
|
|
|
The `system` operator allows you to run an external command and use its output as a value in your expression.
|
|
|
|
**Security warning**: The system operator is disabled by default. You must explicitly pass `--security-enable-system-operator` to use it.
|
|
|
|
**Note:** When enabled, the system operator can replicate the functionality of `env` and `load`
|
|
operators via external commands. Enabling it effectively overrides `--security-disable-env-ops`
|
|
and `--security-disable-file-ops`.
|
|
|
|
## Usage
|
|
|
|
```bash
|
|
yq --security-enable-system-operator --null-input '.field = system("command"; "arg1")'
|
|
```
|
|
|
|
The operator takes:
|
|
- A command string (required)
|
|
- An argument (or an array of arguments), separated from the command by `;` (optional)
|
|
|
|
The current matched node's value is serialised and piped to the command via stdin. The command's stdout (with trailing newline stripped) is returned as a string.
|
|
|
|
## Disabling the system operator
|
|
|
|
The system operator is disabled by default. When disabled, an error is returned instead of running the command, consistent with `--security-disable-env-ops` and `--security-disable-file-ops`.
|
|
|
|
Use `--security-enable-system-operator` flag to enable it.
|
|
|
|
## system operator returns error when disabled
|
|
Use `--security-enable-system-operator` to enable the system operator.
|
|
|
|
Given a sample.yml file of:
|
|
```yaml
|
|
country: Australia
|
|
```
|
|
then
|
|
```bash
|
|
yq '.country = system("/usr/bin/echo"; "test")' sample.yml
|
|
```
|
|
will output
|
|
```bash
|
|
Error: system operations are disabled, use --security-enable-system-operator to enable
|
|
```
|
|
|
|
## Run a command with an argument
|
|
Use `--security-enable-system-operator` to enable the system operator.
|
|
|
|
Given a sample.yml file of:
|
|
```yaml
|
|
country: Australia
|
|
```
|
|
then
|
|
```bash
|
|
yq --security-enable-system-operator '.country = system("/bin/echo"; "test")' sample.yml
|
|
```
|
|
will output
|
|
```yaml
|
|
country: test
|
|
```
|
|
|
|
## Run a command without arguments
|
|
Omit the semicolon and args to run the command with no extra arguments.
|
|
|
|
Given a sample.yml file of:
|
|
```yaml
|
|
a: hello
|
|
```
|
|
then
|
|
```bash
|
|
yq --security-enable-system-operator '.a = system("/bin/echo")' sample.yml
|
|
```
|
|
will output
|
|
```yaml
|
|
a: ""
|
|
```
|
|
|