nl command
syntax

nl [options] [file]

為檔案的內容編定列號後輸出其結果.此命令除可為本文(body)
編定列號外,亦可以透過選項的設定,對一班不編定列號的
標頭 (header) 與  標尾(footer) 進行編號.
列號的編訂乃是以邏輯頁面(logical page)為單位;一個邏輯頁面
是由標頭,本文,與標尾三個部份組成.於所想處理的檔案中,這三個
部份依序是由特殊的字串
\:\:\:
\:\:
\:
這三個來予以界定.

常用選項
-b, --body-numbering=STYLE
              use STYLE for numbering body lines

       -d, --section-delimiter=CC
              use CC for separating logical pages

       -f, --footer-numbering=STYLE
              use STYLE for numbering footer lines

       -h, --header-numbering=STYLE
              use STYLE for numbering header lines

       -i, --page-increment=NUMBER
              line number increment at each line

       -l, --join-blank-lines=NUMBER
              group of NUMBER empty lines counted as one

       -n, --number-format=FORMAT
              insert line numbers according to FORMAT
-p, --no-renumber
              do not reset line numbers at logical pages

       -s, --number-separator=STRING
              add STRING after (possible) line number

       -v, --first-page=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

       pREGEXP
              number only lines that contain a match for REGEXP

       FORMAT is one of:

       ln     left justified, no leading zeros

       rn     right justified, no leading zeros

       rz     right justified, leading zeros

AUTHOR
       Written by Scott Bartram and David MacKenzie.

REPORTING BUGS
       Report bugs to <bug-coreutils@gnu.org>.