第83页 | Learning the Bash Shell | 阅读 ‧ 电子书库

同步阅读进度,多语言翻译,过滤屏幕蓝光,评论分享,更多完整功能,更好读书体验,试试 阅读 ‧ 电子书库

Shell Variables

bash derives much of its programming functionality from shell variables. We've already seen the basics of variables. To recap briefly: they are named places to store data, usually in the form of character strings, and their values can be obtained by preceding their names with dollar signs ($). Certain variables, called environment variables, are conventionally named in all capital letters, and their values are made known (with the export statement) to subprocesses.

If you are a programmer, you already know that just about every major programming language uses variables in some way; in fact, an important way of characterizing differences between languages is comparing their facilities for variables.

The chief difference between bash's variable schema and those of conventional languages is that bash's places heavy emphasis on character strings. (Thus it has more in common with a special-purpose language like SNOBOL than a general-purpose one like Pascal.) This is also true of the Bourne shell and the C shell, but bash goes beyond them by having additional mechanisms for handling integers explicitly.

请支持我们,让我们可以支付服务器费用。
使用微信支付打赏


上一页 · 目录下一页


下载 · 书页 · 阅读 ‧ 电子书库