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# **head**
```markdown
用法head [选项]... [文件]...
Print the first 10 lines of each FILE to standard output.
With more than one FILE, precede each with a header giving the file name.
With no FILE, or when FILE is -, read standard input.
Mandatory arguments to long options are mandatory for short options too.
-c, --bytes=[-]K print the first K bytes of each file;
with the leading '-', print all but the last
K bytes of each file
-n, --lines=[-]K print the first K lines instead of the first 10;
with the leading '-', print all but the last
K lines of each file
-q, --quiet, --silent 不显示包含给定文件名的文件头
-v, --verbose 总是显示包含给定文件名的文件头
K 后面可以跟乘号:
b 512, kB 1000, K 1024, MB 1000*1000, M 1024*1024,
GB 1000*1000*1000, G 1024*1024*1024, 对于T, P, E, Z, Y 同样适用
```
## 实例
```bash
head -1 file # 显示file文件第一行
head -n1 /etc/issue # 查看操作系统版本,不一定每个系统都能看到
```