命令行选项和参数

运行NCL时，可以使用一些选项来改变NCL解释器的默认行为。 同时给脚本传入命令行参数来指定程序中的变量值，这使得编写的脚本能够更加有效。

选项

NCL预定义的选项包括：

  • -f : 在可能的情况下使用新的文件结构和NetCDF4特征
  • -h : 打印此命名行选项帮助信息并退出
  • -n : 使用print函数时，不显示元素序号
  • -o : 对于某些向后不兼容的改变保留从前的行为
  • -p : 关闭 system() 函数在页面上的输出
  • -x : 回调NCL命令，进入命令行时将回调所有自动载入的函数（6.2.0版以上）
  • -Q : 关闭NCL版本和版权信息显示
  • -V : 打印NCL版本并退出
-h
$ ncl -h
  Usage: ncl -fhnopxQV <args> <file.ncl>
     -f: use new file structure and NetCDF4 features when possible
     -h: print this message and exit
     -n: don't enumerate values in print()
     -o: retain former behavior for certain backwards-incompatible changes
     -p: don't page output from the system() command
     -x: echo NCL commands
     -Q: turn off echo of NCL version and copyright info
     -V: print NCL version and exit
-n
$ ncl -n
 Copyright (C) 1995-2015 - All Rights Reserved
 University Corporation for Atmospheric Research
 NCAR Command Language Version 6.3.0
 The use of this software is governed by a License Agreement.
 See http://www.ncl.ucar.edu/ for more details.
ncl 0> f = addfile("T2m.nc", "r")
ncl 1> T = f->T
ncl 2> print(T)

将输出:

Variable: T
Type: float
Total Size: 72192 bytes
            18048 values
Number of Dimensions: 3
Dimensions and sizes:   [time | 1] x [lat | 94] x [lon | 192]
Coordinates:
            time: [197901..197901]
            lat: [-88.54195..88.54195]
            lon: [ 0..358.125]
Number Of Attributes: 4
  units :       K
  short_name :  T2m
  long_name :   Temperature (2m)
  _FillValue :  1e+36
255.49
255.44
255.39
255.34
255.3
     [...]
234.23
234.16
234.09
234.02
233.95
233.88
-x
$ ncl -x
 Copyright (C) 1995-2015 - All Rights Reserved
 University Corporation for Atmospheric Research
 NCAR Command Language Version 6.3.0
 The use of this software is governed by a License Agreement.
 See http://www.ncl.ucar.edu/ for more details.
ncl 0> a = 5
+ a = 5
ncl 1> exit
+ exit
-Q
$ ncl -Q
ncl 0>
-V
$ ncl -V
6.3.0

参数

命令行参数是设定变量的简单的NCL语句，变量通过赋值定义。在赋值的等号 = 前后不允许有任何的空白。

例：以下代码赋值两个初始化变量 nyrStrt 和 nyrLast

% ncl nyrStrt=1900 nyrLast=2004
 Copyright (C) 1995-2015 - All Rights Reserved
 University Corporation for Atmospheric Research
 NCAR Command Language Version 6.3.0
 The use of this software is governed by a License Agreement.
 See http://www.ncl.ucar.edu/ for more details.
ncl 0> print(nyrStrt)

Variable: nyrStrt
Type: integer
Total Size: 4 bytes
            1 values
Number of Dimensions: 1
Dimensions and sizes:   [1]
Coordinates:
(0)     1900

同时也可以给初始化变量属性，例:

% ncl nyrStrt=1930 'nyrStrt@long_name="Model Run Begin Year"' 'nyrStrt@units="Years"'
 Copyright (C) 1995-2015 - All Rights Reserved
 University Corporation for Atmospheric Research
 NCAR Command Language Version 6.3.0
 The use of this software is governed by a License Agreement.
 See http://www.ncl.ucar.edu/ for more details.
ncl 0> print(nyrStrt)

Variable: nyrStrt
Type: integer
Total Size: 4 bytes
            1 values
Number of Dimensions: 1
Dimensions and sizes:   [1]
Coordinates:
Number Of Attributes: 2
  units :       Years
  long_name :   Model Run Begin Year
(0)     1930
../_images/donate3.png