NAME

       ncoffsets - print the starting/ending file offsets for netCDF variables

SYNOPSIS

       ncoffsets [-h] | [-x] | [-sgr] [-v var1[,...]]  file

DESCRIPTION

       ncoffsets  prints  the  file  offsets information of variables defined in a given netCDF file. The ending
       offsets reported is an exclusive offset, i.e.  1 byte more than the last byte occupied by  the  variable.
       In  other  words,  the  ending  offset is equal to the sum of starting offset and the variable size.  For
       record variables, only the offsets of first record are printed. Add option -r to print the offsets of all
       records.

       If no argument is given, command usage information is printed.

OPTIONS

       -v var1[,...]
              The output will include data values for the specified variables. One or  more  variables  must  be
              specified  by  name  in the comma-delimited list following this option.  The list must be a single
              argument to the command, hence cannot contain blanks or other white space characters.   The  named
              variables  must  be valid netCDF variables in the input file.  The default, without this option is
              to include data values for all variables in the output.

       -s     Print the variable size in bytes. For record variables, only the size of one record is printed.

       -g     Print the gap in bytes from the previous variable. For the first defined variable, print  the  gap
              from the end of file header. For record variables, there is no gap between records.

       -r     Output  the offset information for all records of the selected record variables.  Without this op‐
              tion, only the offsets of first record are printed.

       -x     Check all fixed-size variable for file space gaps in between any two  immediately  adjacent  vari‐
              ables. It prints "1" on stdout if gaps are found, "0" for otherwise. This option disables all oth‐
              er options.

       -h     Print the available command-line options

EXAMPLES

       Print the file offset information for all variables in a netCDF file.

       % ncoffsets -sg testfile.nc
       netcdf testfile.nc {
       //file format: CDF-1

       file header:
            size   = 340 bytes
            extent = 340 bytes

       dimensions:
            x = 100
            y = 100
            z = 100
            time = UNLIMITED // (100 currently)

       fixed-size variables:
            double square(x, y):
                   start file offset =         340
                   end   file offset =       80340
                   size in bytes     =       80000
                   gap from prev var =           0
            double cube(x, y, z):
                   start file offset =       80340
                   end   file offset =     8080340
                   size in bytes     =     8000000
                   gap from prev var =           0

       record variables:
            double time(time):
                   start file offset =     8080340    (record 0)
                   end   file offset =     8081140    (record 0)
                   size in bytes     =           8    (of one record)
                   gap from prev var =           0
            double xytime(time, x, y):
                   start file offset =     8080348    (record 0)
                   end   file offset =    16080348    (record 0)
                   size in bytes     =       80000    (of one record)
                   gap from prev var =           0
       }

       Check if there are gaps in between two adjacent fixed-size variables.

       % ncoffsets -x testfile.nc
       0

SEE ALSO

       pnetcdf(3)

DATE

       February 21, 2022

Printed: 2025-07-18                              PnetCDF 1.12.3                                     ncoffsets(1)