composer中文镜像配置失败！帮忙看看

bogon:~ apple$ composer config -g repo.packagist

  [InvalidArgumentException]                

  There is no packagist repository defined  

config [-g|--global] [-e|--editor] [-a|--auth] [--unset] [-l|--list] [-f|--file FILE] [--absolute] [--] [<setting-key>] [<setting-value>]...

bogon:~ apple$ composer config -g repo.packagist composer https://packagist.phpcomposer.com

bogon:~ apple$ composer config -g repo.packagist

  [InvalidArgumentException]                

  There is no packagist repository defined  

config [-g|--global] [-e|--editor] [-a|--auth] [--unset] [-l|--list] [-f|--file FILE] [--absolute] [--] [<setting-key>] [<setting-value>]...

bogon:~ apple$ config -gl

-bash: config: command not found

bogon:~ apple$ composer config -g repo.packagist composer https://packagist.phpcomposer.com

bogon:~ apple$ composer config -g repo.packagist

  [InvalidArgumentException]                

  There is no packagist repository defined  

config [-g|--global] [-e|--editor] [-a|--auth] [--unset] [-l|--list] [-f|--file FILE] [--absolute] [--] [<setting-key>] [<setting-value>]...

bogon:~ apple$ composer config -g repo.packagist composer https://packagist.phpcomposer.com

bogon:~ apple$ config -gl

-bash: config: command not found

bogon:~ apple$ 

请问我这边怎么都是 not found呀？都找不到这个东西存在。是不是哪里没配置好还是怎么滴？帮忙帮忙呀！