今天我们来详细讲解下，Linux浏览文件的三种命令，它们分别是：cat、less、more！
cat命令: 一次性在终端中显示文件的所有内容
cat Facebook首席运营官桑德伯格《Lean\ In》.txt
cat命令显示出多少行呢？
参数：n 由 1 开始对所有输出的行数进行编号
cat -n Facebook首席运营官桑德伯格《Lean\ In》.txt
cat命令还可以连接多个文本的内容一起输出
cat -n hello.txt word.txt
less命令: 分页显示文件内容
less和cat最大的区别是：less命令会分一页一页地显示文件内容，cat会一次性全部显示
less Facebook首席运营官桑德伯格《Lean\ In》.txt
这时我们会看到 less命令不会一次性读取 ‘Facebook首席运营官桑德伯格《Lean\ In》.txt’ 文本里的全部内容，而是会分页读取，每一页读取内容的多少是由你的终端大小来决定的
less命令浏览文件的快捷键：
注意：这里快捷键的字母都是区分大小写的
less命令浏览文件高级快捷键的使用
“=”键：显示当前页面的内容是文件中第几行到第几行，按Enter键撤销
Facebook首席运营官桑德伯格《Lean\ In》.txt lines 5-10/287 byte 4308/171635 3% (press RETURN)
下面我们就对这段描述信息座椅详细的解释：
Facebook首席运营官桑德伯格《Lean\ In》.txt: 表示当前正在读取文件的名称
lines 5-10/287： 表示这个文本总共有287行，当前正在读取的是5-10行
byte 4308/171635: 表示文本总共有171635个字符，当前读取了4308个字符
%3： 表示当前读取的内容占了文本内容总共的 %3
h键：进入快捷键的帮助文档，按q键退出
/(斜杠)：进入搜索模式
如：搜索关键字 more
要想在搜索中跳转到下一个符合的内容，可以按n键，按N键可以跳到上一个符合的内容
more命令
more命令和less命令相似，但没有less命令强大
如：more命令不能往后翻页，只能一路往前翻页
这是因为more命令是在less命令之前出现的
注：这是Facebook首席运营官桑德伯格《Lean In》的部分篇章，大家可以用这部分篇章来对cat、less命令做一次动手实操的练习，这样可以帮助大家更好的理解less命令的强大之处
I GOT PREGNANT with my first child in the summer of 2004. At the time, I was running the online sales and operations groups at Google. I had joined the company three and a half years earlier when it was an obscure start-up with a few hundred employees in a run-down office building. By my first trimester, Google had grown into a company of thousands and moved into a multibuilding campus.
My pregnancy was not easy. The typical morning sickness that often accompanies the first trimester affected me every day for nine long months. I gained almost seventy pounds, and my feet swelled two entire shoe sizes, turning into odd-shaped lumps I could see only when they were propped up on a coffee table. A particularly sensitive Google engineer announced that “Project Whale” was named after me.
One day, after a rough morning spent staring at the bottom of the toilet, I had to rush to make an important client meeting. Google was growing so quickly that parking was an ongoing problem, and the only spot I could find was quite far away. I sprinted across the parking lot, which in reality meant lumbering a bit more quickly than my absurdly slow pregnancy crawl. This only made my nausea worse, and I arrived at the meeting praying that a sales pitch was the only thing that would come out of my mouth. That night, I recounted these troubles to my husband, Dave. He pointed out that Yahoo, where he worked at the time, had designated parking for expectant mothers at the front of each building.
The next day, I marched in—or more like waddled in—to see Google founders Larry Page and Sergey Brin in their office, which was really just a large room with toys and gadgets strewn all over the floor. I found Sergey in a yoga position in the corner and announced that we needed pregnancy parking, preferably sooner rather than later. He looked up at me and agreed immediately, noting that he had never thought about it before.
To this day, I’m embarrassed that I didn’t realize that pregnant women needed reserved parking until I experienced my own aching feet. As one of Google’s most senior women, didn’t I have a special responsibility to think of this? But like Sergey, it had never occurred to me. The other pregnant women must have suffered in silence, not wanting to ask for special treatment. Or maybe they lacked the confidence or seniority to demand that the problem be fixed. Having one pregnant woman at the top—even one who looked like a whale—made the difference.