- Practical functions to be used in GMT Bourne Again shell scripts




gmt_clean_up [prefix]

gmt_message message

gmt_abort message

gmt_get_nrecords file(s)

gmt_get_ndatarecords file(s)

gmt_get_nfields string

gmt_get_field string

gmt_get_region file(s) [options]

gmt_get_gridregion file [options]

gmt_get_map_width -R -J

gmt_get_map_height -R -J

gmt_set_psfile file

gmt_set_pdffile file

gmt_set_framename prefix framenumber

gmt_set_framenext framenumber

Description provides a set of functions to Bourne (again) shell scripts in support of GMT. The calling shell script should include the following line, before the functions can be used:


Once included in a shell script, allows GMT users to do some scripting more easily than otherwise. The functions made available are:

Creates a temporary directory in /tmp or (when defined) in the directory specified by the environment variable TMPDIR. The name of the temporary directory is returned as environment variable GMT_TMPDIR. This function also causes GMT to run in ‘isolation mode’, i.e., all temporary files will be created in GMT_TMPDIR and the gmt.conf file will not be adjusted.
Removes the temporary directory and unsets the GMT_TMPDIR environment variable.
Remove all files and directories in which the current process number is part of the file name. If the optional prefix is given then we also delete all files and directories that begins with the given prefix.
Send a message to standard error.
Send a message to standard error and exit the shell.
Returns the total number of lines in file(s)
Returns the total number of data records in file(s), i.e., not counting headers.
Returns the number of fields or words in string
Returns the given field in a string. Must pass string between double quotes to preserve it as one item.
Returns the region in the form w/e/s/n based on the data in table file(s). Optionally add -I*dx*/dy to round off the answer.
Returns the region in the form w/e/s/n based on the header of a grid file. Optionally add -I*dx*/dy to round off the answer.
Expects the user to give the desired -R -J settings and returns the map width in the current measurement unit.
Expects the user to give the desired -R -J settings and returns the map height in the current measurement unit.
Create the output PostScript file name based on the base name of a given file (usually the script name $0).
Returns a lexically ordered filename stem (i.e., no extension) given the file prefix and the current frame number, using a width of 6 for the integer including leading zeros. Useful when creating animations and lexically sorted filenames are required.
Accepts the current frame integer counter and returns the next integer counter.


1. These functions only work in the Bourne shell (sh) and their derivatives (like ash, bash, ksh and zsh). These functions do not work in the C shell (csh) or their derivatives (like tcsh), and cannot be used in DOS batch scripts either.

2. were first introduced in GMT version 4.2.2 and have since been regularly expanded with other practical scripting short-cuts. If you want to suggest other functions, please do so by adding a New Issue request on

See Also

gmt , gmt.conf , gmtinfo , grdinfo