nl 命令

命令简介

nl(Number of Lines)将指定的文件添加行号标注后写到标准输出。如果不指定文件或指定文件为"-" ，程序将从标准输入读取数据。

-b : 指定添加行号的方式，主要有两种：
-b a:表示无论是否为空行，同样列出行号("cat -n"就是这种方式)
-b t:只列出非空行的编号并列出（默认为这种方式）
-n : 设置行号的样式，主要有三种：
-n ln:在行号字段最左端显示
-n rn:在行号字段最右边显示，且不加0
-n rz:在行号字段最右边显示，且加0
-w : 行号字段占用的位数(默认为6位)

image.png

Usage: nl [OPTION]... [FILE]...
Write each FILE to standard output, with line numbers added.
With no FILE, or when FILE is -, read standard input.

Mandatory arguments to long options are mandatory for short options too.
  -b, --body-numbering=STYLE      use STYLE for numbering body lines 使用指定样式编号文件的正文行目
  -d, --section-delimiter=CC      use CC for separating logical pages 使用指定的CC 分割逻辑页数
  -f, --footer-numbering=STYLE    use STYLE for numbering footer lines 使用指定样式编号文件的页脚行目
  -h, --header-numbering=STYLE    use STYLE for numbering header lines 使用指定样式编号文件的页眉行目
  -i, --line-increment=NUMBER     line number increment at each line 设置每一行遍历后的自动递增值
  -l, --join-blank-lines=NUMBER   group of NUMBER empty lines counted as one 设置数值为多少的若干空行被视作一行
  -n, --number-format=FORMAT      insert line numbers according to FORMAT 根据指定格式插入行号
  -p, --no-renumber               do not reset line numbers at logical pages 在逻辑页数切换时不将行号值复位
  -s, --number-separator=STRING   add STRING after (possible) line number 可能的话在行号后添加字符串
  -v, --starting-line-number=NUMBER  first line number on each logical page
  -w, --number-width=NUMBER       use NUMBER columns for line numbers
      --help     display this help and exit
      --version  output version information and exit

By default, selects -v1 -i1 -l1 -sTAB -w6 -nrn -hn -bt -fn.  CC are
two delimiter characters for separating logical pages, a missing
second character implies :.  Type \\ for \.  STYLE is one of:

  a         number all lines
  t         number only nonempty lines
  n         number no lines
  pBRE      number only lines that contain a match for the basic regular
            expression, BRE

FORMAT is one of:

  ln   left justified, no leading zeros
  rn   right justified, no leading zeros
  rz   right justified, leading zeros


GNU coreutils online help: <http://www.gnu.org/software/coreutils/>
For complete documentation, run: info coreutils 'nl invocation'