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From: Bart Schaefer <schaefer@brasslantern.com>
Message-id: <110201121656.ZM18559@torch.brasslantern.com>
Date: Tue, 01 Feb 2011 12:16:56 -0800
In-reply-to: <4D4850F7.6060205@gmail.com>
Comments: In reply to Anonymous bin Ich <ichbinanon@gmail.com>
 "Check existence of a program" (Feb  1, 11:59pm)
References: <4D4850F7.6060205@gmail.com>
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To: zsh-users@zsh.org
Subject: Re: Check existence of a program
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On Feb 1, 11:59pm, Anonymous bin Ich wrote:
}
} % cat notworking.zsh
} #!/bin/zsh
} set -x
} prog="exiftime"
} path=$(which ${prog})

As has already been pointed out, assigning to $path alters the value of
$PATH, which makes it impossible to find any other executables.

One way to prevent yourself from getting into trouble with this:

    readonly path

Now you can still assign to PATH (and the new value is reflected in
the $path array), but you can't accidentally stomp on it via direct
assignment to path.