On the Source Insight command line, you can specify files following the options. Each file name may be optionally preceded by a plus sign (+) and a line number. If this is done, the file will be displayed with that line number visible.
sourceinsight4 +100 file.c
This will open file.c and position the file so that line 100 is visible.
Each file name may be optionally preceded with a plus sign (+) only. In this case, the file is opened along with the other files in the current workspace.
This will open file.c along with all the files previously open in the current workspace.
If one or more files are specified on the command line without the plus sign prefix, then the files previously open in the current workspace are not opened. Instead, only the files specified on the command line are opened.
sourceinsight4 file.c other.c
This will open only file.c and other.c. The previously opened files in the current workspace are not opened.
If you specify a symbol name that does not happen to conflict with a file name, then Source Insight will open the correct file and jump to the definition. For example:
This will open the file containing OpenTcpPort and jump to its definition. You can combine multiple symbols on the command line.
When a relative file name path is given on the command line, Source Insight first tries to find the file relative to the directory that you started Source Insight in. If it can't find the file and a project is open, it looks for the file in the project's file list.
In other words, you can start Source Insight in any directory and give it a file name, and if the file is in the current project, Source Insight should find it. If there happens to be a file with the same name in the startup directory (or relative to it), then Source Insight will open that file.