---
name: "ncoffsets"
section: "1"
platform: "linux"
package: "pnetcdf-openmpi"
version: "1.15.1-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/ncoffsets"
---

# ncoffsets(1)

print the starting/ending file offsets for netCDF variables

## 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 only display the offset information for the specified* *variables. Names of one or more variables must be provided in the* *comma-delimited list which must not contain blanks or other white space* *characters. The named variables must be valid netCDF variables in the input* *file. The default, i.e., without this option, is to display the offset* *information for all variables stored in the input file.*

- **-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 option, only the offsets of first record are printed.*

- **-x**

  *Check all fixed-size variable for file space gaps in between any two* *immediately adjacent variables. It prints "1" on stdout if gaps are found,* *"0" for otherwise. This option disables all other 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
// Number of dimensions: 4
// Number of variables: 4
// Number of global attributes: 0
file header:
    size   = 256 bytes
    extent = 512 bytes
dimensions:
    time = UNLIMITED // (101 currently)
    Z = 100
    Y = 100
    X = 100
fixed-size variables:
    float  square(Y, X):
           start file offset =         512
           end   file offset =       40512
           size in bytes     =       40000
           gap from prev var =         256
    double cube(Z, Y, X):
           start file offset =       40512
           end   file offset =     8040512
           size in bytes     =     8000000
           gap from prev var =           0
record variables:
    double time(time):
           start file offset =     8040512    (0th record)
           end   file offset =     8040520    (0th record)
           size in bytes     =           8    (of one record)
           gap from prev var =           0
    float  rec_var(time, Z, Y, X):
           start file offset =     8040520    (0th record)
           end   file offset =    12040520    (0th record)
           size in bytes     =     4000000    (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)](/pnetcdf/3.md)

## DATE

*September 18, 2026*