In the following examples, function names starting with pipecmd_ or
pipeline_ are real libpipeline functions, while any other function
names are pseudocode.
The simplest case is simple. To run a single command, such as mv
source dest:
pipeline *p = pipeline_new_command_args ("mv", source, dest, NULL);
int status = pipeline_run (p);
libpipeline is often used to mimic shell pipelines, such as the
following example:
zsoelim < input-file | tbl | nroff -mandoc -Tutf8
The code to construct this would be:
pipeline *p;
int status;
p = pipeline_new ();
pipeline_want_infile (p, "input-file");
pipeline_command_args (p, "zsoelim", NULL);
pipeline_command_args (p, "tbl", NULL);
pipeline_command_args (p, "nroff", "-mandoc", "-Tutf8", NULL);
status = pipeline_run (p);
You might want to construct a command more dynamically:
pipecmd *manconv = pipecmd_new_args ("manconv", "-f", from_code,
"-t", "UTF-8", NULL);
if (quiet)
pipecmd_arg (manconv, "-q");
pipeline_command (p, manconv);
Perhaps you want an environment variable set only while running a
certain command:
pipecmd *less = pipecmd_new ("less");
pipecmd_setenv (less, "LESSCHARSET", lesscharset);
You might find yourself needing to pass the output of one pipeline
to several other pipelines, in a 'tee' arrangement:
pipeline *source, *sink1, *sink2;
source = make_source ();
sink1 = make_sink1 ();
sink2 = make_sink2 ();
pipeline_connect (source, sink1, sink2, NULL);
/* Pump data among these pipelines until there's nothing left. */
pipeline_pump (source, sink1, sink2, NULL);
pipeline_free (sink2);
pipeline_free (sink1);
pipeline_free (source);
Maybe one of your commands is actually an in-process function,
rather than an external program:
pipecmd *inproc = pipecmd_new_function ("in-process", &func,
NULL, NULL);
pipeline_command (p, inproc);
Sometimes your program needs to consume the output of a pipeline,
rather than sending it all to some other subprocess:
pipeline *p = make_pipeline ();
const char *line;
pipeline_want_out (p, -1);
pipeline_start (p);
line = pipeline_peekline (p);
if (!strstr (line, "coding: UTF-8"))
printf ("Unicode text follows:0);
while (line = pipeline_readline (p))
printf (" %s", line);
pipeline_free (p);
