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hymie
Asked: 2018-02-14 05:16:49 +0800 CST

BackupPC -- PingPath and PingCmd

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BackupPC has two configuration variables:

$Conf{PingPath} = '/bin/ping';
Full path to the ping command.

$Conf{PingCmd} = '$pingPath -c 1 $host';
Ping command. The following variables are substituted at run-time:
  $pingPath      path to ping ($Conf{PingPath})
  $host          host name

I'm just trying to understand why there are two separate variables. That is, what benefit does this setup provide as opposed to just a single variable

$Conf{PingCmd} = '/bin/ping -c 1 $host';
backuppc

1 Answers

  1. To me that looks like an improvement iteration where somebody ran into portability issues with ping either not installed in the default $PATH or not in /bin/ and then deciding to make the absolute path to ping a configurable parameter, which would only need updating in one place.

    Creating a new parameter when that parameter will be referenced only once, that may seem a bit redundant, but maybe that wasn't known beforehand or it is simply a (personal) coding style preference.
    Since parameter expansion/substitution is cheap doing that is not harmful.

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