Change individual GMT default settings


gmt set [ -C | -D[s|u] | -Gdefaultsfile ] [ -[BJRXYp]value ] PARAMETER1 value1 PARAMETER2 value2 PARAMETER3 value3

Note: No space is allowed between the option flag and the associated arguments.


set will adjust individual GMT defaults settings in the current directory’s gmt.conf file (under classic mode) or in the current session directory (modern mode). If no such file exists one will be created. The main purpose of set is temporarily to change certain parameters inside a shell script, e.g., set the map frame type to plain, run the script, and reset to fancy. Only parameters that differ from the GMT SI system defaults will be written. Optionally, you can specify one or more temporary changes directly on any GMT command line with the syntax --PARAMETER=VALUE; such changes are only in effect for that command and do not permanently change the default settings on disk.

Required Arguments


Provide one or several pairs of parameter/value combinations that you want to modify. For a complete listing of available parameters and their meaning, see the gmt.conf man page.

Optional Arguments


Convert a .gmtdefaults4 file created by GMT4 to a gmt.conf file used by modern GMT. The original file is retained.


Modify the GMT defaults based on the system settings. Append u for US defaults or s for SI defaults. [-D alone gives the version selected at compile time]


Name of specific gmt.conf file to read and modify [Default looks first in current directory, then in your home directory, then in ~/.gmt and finally in the system defaults].


Set the expansion of any of these shorthand options.

-^ or just -

Print a short message about the syntax of the command, then exit (NOTE: on Windows just use -).

-+ or just +

Print an extensive usage (help) message, including the explanation of any module-specific option (but not the GMT common options), then exit.

-? or no arguments

Print a complete usage (help) message, including the explanation of all options, then exit.


Temporarily override a GMT default setting; repeatable. See gmt.conf for parameters.


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