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30 lines
771 B
Markdown
30 lines
771 B
Markdown
# Replace The Current Process With An External Command
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Ruby's
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[`Kernel#exec`](http://ruby-doc.org/core-2.2.3/Kernel.html#method-i-exec)
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method can be used to run an external command. What differentiates it from
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executing commands with the likes of back ticks or `%x[]` is that instead of
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forking a child process, it replaces the current process.
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For instance, the following ruby script, when executed, will replace itself
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with an `irb` session.
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```ruby
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Kernel.exec('irb')
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```
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The external command will even benefit from the existing environment. For
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example, if I set the following environment variable
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```bash
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$ export GREETING=hello
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```
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and then execute a file containing
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```ruby
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Kernel.exec('echo $GREETING')
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```
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I can expect to see `hello` printed to stdout.
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