在shell中自定义完成

Question

I need to develop a utility that will take command line arguments as follows:

$ lsm  -g <group> -t <type> -d <device>

My project manager wants that when we type any argument like lsm -g and press Tab , then a function will be called to run a database query and fetch help for the user about the value of the option.

Similar to how terminal behaves in this case:

$ cd <tab>
.bash_history                   .local/
.bash_logout                    .log-report.log.swp
.bash_profile                   .macromedia/
.bashrc                         .mozilla/
.cache/                         Music/
.config/                        .mysql_history
.dbus/                          .nautilus/
Desktop/                        .opera/
Documents/                      .orc/
Downloads/                      .p2/
.eclipse/                       Pictures/

I have tried these approaches:

1. Use fork() to create a child to call the help function.
2. Use execv() to run a help function using a seperate binary.

But both require that lsm be running.

I'm not sure how to proceed further.

Answer 1

As various commentators have noted, tab-completion is implemented in the shell, not in the program which is about to be executed.

Most shells have frameworks for implementing custom tab-completion. In the case of bash , it is implemented with the help of the readline library. There is extensive documentation in the bash manual and there are a variety of tutorials kicking around the internet, such as this one from Debian (not an endorsement, just the result of a quick Google search).