Início / server / Perguntas / 986840
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425nesp
Asked: 2019-10-05 14:08:53 +0800 CST

Como o systemd pede às unidades para recarregar a configuração?

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Eu estava lendo a página de manual systemctl reloade encontrei esta frase sobre reload.

reload PATTERN...
    Asks all units listed on the command line to reload their
    configuration.

http://man7.org/linux/man-pages/man1/systemctl.1.html

Como o systemd faz isso? Qual API o systemd usa para pedir a uma unidade que recarregue sua configuração?

também encontrei reload-or-restart.

 reload-or-restart PATTERN...
     Reload one or more units if they support it. If not, restart them
     instead.

Como o systemd sabe se a unidade suporta recarga?

systemd

1 respostas

  1. Best Answer

    Aqui está o que a página man systemd.servicediz sobre recarregar:

           ExecReload=
           Commands to execute to trigger a configuration reload in the 
           service. This argument takes multiple command lines, following
           the same scheme as described for ExecStart= above. Use of
           this setting is optional. Specifier and environment variable
           substitution is supported here following the same scheme as
           for ExecStart=.

           One additional, special environment variable is set: if known,
           $MAINPID is set to the main process of the daemon, and may
           be used for command lines like the following:

               /bin/kill -HUP $MAINPID

           Note however that reloading a daemon by sending a signal
           (as with the example line above) is usually not a good
           choice, because this is an asynchronous operation and hence
           not suitable to order reloads of multiple services against
           each other. It is strongly recommended to set ExecReload=
           to a command that not only triggers a configuration reload
           of the daemon, but also synchronously waits for it to complete.

    (A única maneira de saber que systemd.serviceé a página de manual correta para procurar foi no Google para ExecReload, uma string que adivinhei depois de pesquisar o código-fonte do Systemd.)

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