Linux fold命令

mytomorrow

Linux fold命令用于限制文件列宽。

fold指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指令会从标准输入设备读取数据。
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8 j2 h$ H! O6 A' H语法

- C  _8 S% X) z) Lfold [-bs][-w<每列行数>][--help][--version][文件...]
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参数：

-b或--bytes 以Byte为单位计算列宽，而非采用行数编号为单位。
* f+ Z8 U' b% ]" @: P& }3 ]-s或--spaces 以空格字符作为换列点。
' l% X8 b& `. F-w<每列行数>或--width<每列行数> 设置每列的最大行数。
--help 在线帮助。
) q2 J' b7 g- f--version 显示版本信息。
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3 a0 w( z0 Y  J1 G实例

将一个名为testfile 的文件的行折叠成宽度为30，可使用如下命令：
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fold -w 30 testfile
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6 {; s- W: }$ R% w; D# v0 {- f# x# G为了对比，先将testfile文件输出如下：

$ cat testfile #查看testfile 中的内容  
Linux networks are becoming more and more common, but
security is often an overlooked  
6 \1 R) X# Z/ J$ fissue. Unfortunately, in today’s environment all networks
are potential hacker targets,  
$ L7 Z; \% D- C' e$ q* Wfrom top-secret military research networks to small home LANs.  
0 X& C7 }0 d, XLinux Network Security focuses on securing Linux in a
1 h( o$ {7 `1 X1 Y' d1 @; fnetworked environment, where the  
security of the entire network needs to be considered
% l! q" l+ _/ P0 @$ Trather than just isolated machines.  
: m; \3 {- r# `! [# I: U1 NIt uses a mix of theory and practical techniques to
1 F9 m. J% Y8 u0 I8 |' Hteach administrators how to install and  
use security applications, as well as how the
applications work and why they are necessary.

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然后使用fold命令折叠显示：
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  f. U* K" Y5 y5 L3 n( {6 p$ fold -w 30 testfile #行折叠成宽度为30，显示testfile 文件  
Linux networks are becoming mo  
! U2 j2 D  a7 y) i" R/ d+ t- pre and more common, but securi  
8 @  x9 K, o' cty is often an overlooked issu  
e. Unfortunately, in today’s  
environment all networks are  
potential hacker targets, from  
top-secret military research  
2 O$ @$ G0 m+ ?. }  Y+ N& Nnetworks to small home LANs.  
Linux Network Security focuses  
# q4 P' Z4 z& c3 t: b5 Eon securing Linux in a networ  
ked environment, where the sec  
* c* X" I4 l( K7 O2 ]2 I2 Hurity of the entire network ne  
# |$ J2 h/ B+ y9 |' h3 S8 w% Oeds to be considered rather th  
an just isolated machines. It  
' k( q) @0 Q2 Q8 Z  T5 r& L$ Iuses a mix of theory and pract  
9 n5 |2 `' [$ w0 M, s, X" i% ]ical techniques to teach admin  
5 f9 Q# b3 _% F: y$ X- Wistrators how to install and u  
5 t5 F7 i1 C2 m1 S' u$ cse security applications, as w  
ell as how the applications wo  
rk and why they are necessary
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regngfpcb

fold指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

yin123

Linux fold命令用于限制文件列宽

AustCor1

Linux fold命令