第二个tar命令从stdin读取归档文件并进行展开，展开(x)选项后面使用的连字号表示stdin。

The second tar reads an archive from stdin and expands it in place; the hyphen used with the extract (x) option refers to stdin.

youdao

词条al(阿拉)可以写为el(艾拉)，它可以直接通过使用连字号或空格与人的姓氏写在一起，或省掉不写。

The article al (also written as el) may be attached to surnames directly, separated from surnames with a hyphen or a space, or omitted altogether.

youdao

词条al(阿拉)可以写为el(艾拉)，它可以直接通过使用连字号或空格与人的姓氏写在一起，或省掉不写。

The article al (also written as el) may be attached to surnames directly, separated from surnames with a hyphen or a space, or omitted altogether.

youdao