SUMMARY

Load an external command.

external commands and load require extra work in the linux version of SAC.

SYNTAX

LOAD comname {ABBREV abbrevname}

INPUT

comname:	The name of an external function to load from a shared object.
ABBREV abbrevname:
	An abbreviation or alias for comname.

DESCRIPTION

This command allows the user to load commands written to the SAC external command interface specification (See EXTERNAL_INTERFACE help page). This command must be a function stored in a shared object library ( a .so file- see UNIX LD manpage for details ). SAC will look in all shared object libraries listed in environmental variable SACSOLIST. This environmental variable should contain one or more names of shared objects in a blank delimited list. The path to these shared objects must be specified in the LD_LIBRARY_PATH environmental variable. If SACSOLIST is not set, then SAC will look for a shared object library called libsac.so, using the paths specified in LD_LIBRARY_PATH. A library called libcom.so is distributed with SAC (see EXTERNAL COMMAND section below).

EXAMPLE

Set up your environment to have SAC look in the current directory for a command named foo from a shared object called libbar.so. Set up an alias for foo called myfft.:

% setenv SACSOLIST "libcom.so libbar.so"
#  Add the current directory to the search path.
% setenv LD_LIBRARY_PATH {$LD_LIBRARY_PATH}:.

% sac
SAC> load foo abbrev myfft         * load the command
SAC> read file1.z file2.z file3.z  * input files to pass to the command
SAC> myfft real-imag               * invoke command with its arguments,
                                   * commands must parse their own args.
SAC> psp

How to create a shared object library containing your command(s): Solaris:

cc -o libxxx.so -G extern.c foo.c bar.c

SGI:

cc -g -o libxxx.so -shared foo.c bar.c

LINUX: (gcc):

gcc -o libxxx.so -shared extern.c foo.c bar.c sac.a

where sac.a is the sac library available where you got sac.

EXTERNAL COMMAND INCLUDED IN THE DISTRIBUTION OF SAC

There is one external command which is distributed with SAC. It is called FLIPXY. FLIPXY takes as input one or more X-Y datafiles, and transposes the data. This command is in libcom.so in ${SACAUX}/external along with the source code of FLIPXY for reference. To load FLIPXY, libcom.so must be included in SACSOLIST.

ERRORS

• 1028: External command does not exist:

  • This means that SAC did not find your external command.

  This error can arise for a couple of reasons. One possibility is that your LD_LIBRARY_PATH environmental variable does not contain the path to your shared library. Another possibility is that you have not set your SACSOLIST environmental variable to contain the names of your shared libraries.

LATEST REVISION

March 21, 1996 (Version 00.50)