lianshell

Project description

lianshell is a standalone procedurally designed UNIX-based shell program that supports the following features:

Support for built-in commands including:
- changing working directory
- modifying environment variables
- killing all subprocesses
Runs external programs from any specified location in the file system
Sequential execution of multiple processes
Redirection of output from a process to a file
Run processes in the background
Implement piping of output from one program to another
Handles signal interrupts, including SIGINT and SIGTSTP.

Issues

More signal handling
Auto-completion of commands
Use ncurses
TERM environment variable needs to be set

System calls used

chdir() : to change working directory
fork() : to create a subprocess
execve() : to execute a process
_exit() : to exit a process
wait() : to wait for a process to terminate
open() / close() : to open or close a file descriptor
dup2() : duplicate a file descriptor to another
pipe() : establish a pipe between two processes
kill() : send a signal to a process

Testing procedure

lianshell was tested by running various commands individually as well as in combination with other commands. Valgrind was used to test for memory leaks in the heap and stack memory. htop and pstree were also used to maintain subprocess construction and destruction.

References