Linux shell fold 命令
Linux shell fold命令用于限制文件列宽。
fold 命令会从指定的文件里读取内容，将超过限定列宽的列加入增列字符后，输出到标准输出设备。
若不指定任何文件名称，或是所给予的文件名为 -，则 fold 命令会从标准输入设备读取数据。
fold 命令语法格式
fold [-bs][-w<每列行数>][--help][--version][文件...]
参数
- -b , --bytes
- 以Byte为单位计算列宽，而非采用行数编号为单位。
- -s , --spaces
- 以空格字符作为换列点
- -w<每列行数> , --width<每列行数>
- 设置每列的最大行数
- --help
- 在线帮助
- --version
- 显示版本信息
范例
假设存在 demo6.txt 文件，内容如下
[root@localhost ~/shell]# cat demo6.txt Linux networks are becoming more and more common, but security is often an overlooked issue. Unfortunately, in today’s environment all networks are potential hacker targets, from top-secret military research networks to small home LANs. Linux Network Security focuses on securing Linux in a networked environment, where the security of the entire network needs to be considered rather than just isolated machines. It uses a mix of theory and practical techniques to teach administrators how to install and use security applications, as well as how the applications work and why they are necessary.
然后使用 fold 命令 以每行宽度 30 字符折行
[root@localhost ~/shell]# fold -w 30 demo6.txt Linux networks are becoming mo re and more common, but security is often an overlooke d issue. Unfortunately, in today ’s environment all networks are potential hacker targets, from top-secret military resea rch networks to small home LAN s. Linux Network Security focuses on securing Linux in a networked environment, where t he security of the entire network needs to be considered rather than just isolated mach ines. It uses a mix of theory and pr actical techniques to teach administrators how to in stall and use security applications, as well as how the applications work and why they are necessary.