---
name: "grdedit"
section: "1"
platform: "linux"
package: "gmt-manpages"
version: "3.4-1"
release: "Debian 3.0 (Woody)"
platforms: ["linux"]
url: "https://new.carta.tech/grdedit"
---

# grdedit(1)

Modifying the header in a 2-D grdfile

## NAME

grdedit - Modifying the header in a 2-D grdfile

## SYNOPSIS

**grdedit** *grdfile* \[ **-A** \] \[ **-D***xunit/yunit/zunit/scale/offset/title/remark* \] \[ **-R***west/east/south/north*\[**r**\] \] \[ **-S** \] \[ **-V** \]

## DESCRIPTION

**grdedit** reads the header information in a binary 2-D grdfile and replaces the information with values provided on the command line \[if any\]. As an option, global, geographical grids (with 360 degrees longitude range) can be rotated in the east-west direction. **grdedit** only operates on files containing a grdheader.\
\
         No space between the option flag and the associated arguments. Use upper case for the option flags and lower case for modifiers.

- *grdfile*

  Name of the 2-D grdfile to modify

## OPTIONS

- **-A**

  If necessary, adjust the file's *x\_inc, y\_inc* to be compatible with its domain (or a new domain set with **-R**).  Older gridfiles (i.e., created prior to GMT 3.1) often had excessive slop in' *x\_inc, y\_inc* and an adjustment is necessary. Newer files are created correctly.

- **-D**

  Give new values for *xunit, yunit, zunit, scale, offset, title,* and *remark*. To leave some of the values untouched, specify = as the new value.

- **-R**

  *west, east, south,* and *north* specify the Region of interest. To specify boundaries in degrees and minutes \[and seconds\], use the dd:mm\[:ss\] format. Append **r** if lower left and upper right map coordinates are given instead of wesn. The new w/e/s/n values will replace those in the grid, and the *x\_inc, y\_inc* values are adjusted, if necessary.

- **-S**

  For global, geographical grids only. Grid values will be shifted laterally according to the new borders given in **-R**.

- **-V**

  Selects verbose mode, which will send progress reports to stderr \[Default runs "silently"\].

## EXAMPLES

Let us assume the file data.grd covers the area 300/310/10/30. We want to change the boundaries from geodetic longitudes to geographic and put a new title in the header. We accomplish this by\

grdedit data.grd **-R**-60/-50/10/30 **-D**=/=/=/=/=/"Gravity Anomalies"/=\

The grid world.grd has the limits 0/360/-72/72. To shift the data so that the limits would be -180/180/-72/72, use\

grdedit world.grd **-R**-180/180/-72/72 **-S**\

The file junk.grd was created prior to GMT 3.1 with incompatible **-R** and **-I** arguments. To reset the x- and y-increments we run\

grdedit junk.grd **-A**

## SEE ALSO

*gmt*(l), *grd2xyz*(l), *xyz2grd*(l)