SIMPLE SHELL

Run as:

gcc -Wall -Werror -Wextra -pedantic std=gnu89 *.c -o shell

In interactive mode:

$ ./shell
 $ /bin/ls
 shell main.c shell.c
 $ ls
 shell main.c shell.c
 $ exit
$

In non-interactive mode

$ echo "/bin/ls" | ./shell
shell main.c shell.c
$
$ cat test_ls
/bin/ls
/bin/echo hello
$
$ cat test_ls | ./shell
shell main.c shell.c
hello

Key man pages used or intended:

• getline / strtok
• execve / fork / wait
• isatty
• exit
• access
• signal / kill
• stat
• fflush
• open / read / write / close
• malloc / free
• opendir / readdir / closedir
• chdir / getcwd
• perror

Features Implemented

Handles PATH directories i.e:

$ ./shell
 $ /bin/ls
 shell main.c shell.c
 $
 $ ls
 shell main.c shell.c

Prints current environment with env

$ ./shell
 $ env
 USER=blah
 LANGUAGE=en_US
 SESSION=ubuntu
 COMPIZ_CONFIG_PROFILE=ubuntu
 SHLVL=1
 HOME=/home/blah

Exits terminal

exit [opt status]
Ctrl+D
Ctrl+C

Sets an environment variable

setenv [name] [value]

Deletes an environment variable

unsetenv [name]

Changes directory, updates environment variable PWD

cd [dir]

Commands separator ;

Shell logical operators || and &&

Implements the alias built in command

Usage: `alias [name[='value']]

Handles variable replacement with $

$ ls /var
backups  cache  crash  lib  local  lock  log  mail  metrics  opt  run  snap  spool  tmp
$ echo $?
0
$ echo $$
5104

Handles Comments

$ echo $$ # ls -la
5114

Handles input passed as file

Usage: shell [filename]
$ cat commands
ls
echo hello
env
$
$ ./shell commands
shell main.c shell.c
hello
USER=blah
LANGUAGE=en_US
SESSION=ubuntu
COMPIZ_CONFIG_PROFILE=ubuntu
SHLVL=1
HOME=/home/blah