2023-04-16 10:04:24 +02:00
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# The readonly builtin command
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## Synopsis
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readonly [-p] [-a] [-A] [-f] [NAME[=VALUE] ...]
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## Description
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The `readonly` builtin command is used to mark variables or functions as
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read-only, which means unchangeable. This implies that it can't be unset
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anymore. A `readonly` variable may not be redefined in child scopes. A
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readonly global may not be redefined as a function local variable.
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Simple command environment assignments may not reference readonly
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variables.
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### Options
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| Option | Description |
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|:-------|:-----------------------------------------------------------------------------------------------------------------------|
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| `-a` | refer to normal arrays |
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| `-A` | refer to associative arrays |
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| `-f` | refer to functions |
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| `-p` | print all read-only variables or functions, `-a`, `-A` and `-f` can be used to filter. The output is reusable as input |
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An argument of `--` disables further option processing.
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### Return status
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| Status | Reason |
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|:-------|:-------------------------------|
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| 0 | no error |
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| !=0 | invalid option |
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| !=0 | invalid combination of options |
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| !=0 | a given `NAME` is invalid |
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## Examples
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## Portability considerations
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- in POSIX(r), only the `-p` option is specified
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## See also
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2023-04-24 13:31:29 +02:00
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- [declare](/commands/builtin/declare.md)
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