shell-v2

Shell Version 2 - A re-creation of a UNIX shell using C.

Download and Run Instructions

Clone Repo:

$ git clone https://github.com/SravanthiSinha/shell-v2.git

Compile:

$ make

Run the Executable:

$ ./hsh

To find all about features supported, run the manual:

$ man ./man_1_hsh

To run tests use run_checks.bash $foldername of tests:

$ ./run_checks.bash $folderno

Development details

The project concepts are explored in

• https://github.com/SravanthiSinha/EYNTK-SHELL/blob/master/EYNTK-Shell-v1/README.md

• https://github.com/SravanthiSinha/EYNTK-SHELL/blob/master/EYNTK-Shell-v2/README.md

hsh 1.0 +

A UNIX command line interpreter.

Usage: hsh

• Displays a prompt and wait for the user to type a command. A command line always ends with a new line.
• The prompt is displayed again each time a command has been executed.
• If an executable cannot be found, prints an error message and display the prompt again.
• Handle errors.
• Handles the "end of file" condition (Ctrl+D)
• Handles command lines with arguments
• Handles and parse the PATH environment variable

Builtins

Implemented the built-in command exit:

• exit built-in behaves exactly like sh's
• Handles arguments

Implemented the built-in command cd:

• Changes the current directory of the process.
• Command syntax: cd [path]
• If no argument is given to cd the command is interpreted like cd $HOME
• Handles the command cd -

Implemented the built-in command env:

• Prints the current environment

Implemented the built-in command setenv:

• Sets the environment variable

Implemented the built-in command unsetenv:

• Unset/remove the environment variable

Redirections

Handles the stream redirections **>, < , >> , << , | **

Usage:

[command]> file Redirect standard output to file.

[command]>> file Append standard output to file.

[command]< file Redirect standard input from file.

[command] | [command2..] Redirect command output input of command2

The following redirection is often called a here-document.

[command]<< delimiter

here-doc-text ...

delimiter

$ echo Holberton School > test
$ cat -e test
Holberton School$
$
$ rm -f test
$ echo Holberton School >> test
$ cat -e test
Holberton School$
$ echo Holberton School >> test
$ cat -e test
Holberton School$
Holberton School$
$ cat -e small_file
Holberton$
Second line$
$ rev < small_file
notrebloH
enil dnoceS
$
$ cat -e << HOLBERTON
> qwertyuiop
> ls -l                          
> cat -e small_file
> HOLBERTONnope
> nopeHOLBERTON
> HOLBERTON
> HOLBERTON
qwertyuiop$
ls -l$
cat -e small_file$
HOLBERTONnope$
nopeHOLBERTON$
HOLBERTON $
$
$ ls /var | rev
spukcab
ehcac
hsarc
bil
lacol
kcol
gol
liam
scirtem
tpo
nur
loops
pmt
$ ls -lr /var | cat -e
total 44$
drwxrwxrwt  2 root root     4096 Aug 28 21:53 tmp$
drwxr-xr-x  9 root root     4096 Aug  3  2016 spool$
lrwxrwxrwx  1 root root        4 Jun  5 17:51 run -> /run$
drwxr-xr-x  2 root root     4096 Aug  3  2016 opt$
drwxrwsrwt  2 root whoopsie 4096 Aug  3  2016 metrics$
drwxrwsr-x  2 root mail     4096 Aug  3  2016 mail$
drwxrwxr-x 14 root syslog   4096 Aug 28 10:56 log$
lrwxrwxrwx  1 root root        9 Jun  5 17:51 lock -> /run/lock$
drwxrwsr-x  2 root staff    4096 Apr 10  2014 local$
drwxr-xr-x 73 root root     4096 Aug 12 18:06 lib$
drwxrwsrwt  2 root whoopsie 4096 Aug 28 14:56 crash$
drwxr-xr-x 17 root root     4096 Aug  3  2016 cache$
drwxr-xr-x  2 root root     4096 Aug 24 10:24 backups$

Control operators

Handles the commands separator ; , && , ||

$ ls /var ; ls /var
backups  cache  crash  lib  local  lock  log  mail  metrics  opt  run  spool  tmp
backups  cache  crash  lib  local  lock  log  mail  metrics  opt  run  spool  tmp
$ ls /hbtn ; ls /var
ls: cannot access /hbtn: No such file or directory
backups  cache  crash  lib  local  lock  log  mail  metrics  opt  run  spool  tmp
$ ls /var ; ls /hbtn
backups  cache  crash  lib  local  lock  log  mail  metrics  opt  run  spool  tmp
ls: cannot access /hbtn: No such file or directory
$ ls /var ; ls /hbtn ; ls /var ; ls /var
backups  cache  crash  lib  local  lock  log  mail  metrics  opt  run  spool  tmp
ls: cannot access /hbtn: No such file or directory
backups  cache  crash  lib  local  lock  log  mail  metrics  opt  run  spool  tmp
backups  cache  crash  lib  local  lock  log  mail  metrics  opt  run  spool  tmp
$
$ ls /var && ls /var
backups  cache  crash  lib  local  lock  log  mail  metrics  opt  run  spool  tmp
backups  cache  crash  lib  local  lock  log  mail  metrics  opt  run  spool  tmp
$ ls /hbtn && ls /var
ls: cannot access /hbtn: No such file or directory
$ ls /var && ls /var && ls /var && ls /hbtn
backups  cache  crash  lib  local  lock  log  mail  metrics  opt  run  spool  tmp
backups  cache  crash  lib  local  lock  log  mail  metrics  opt  run  spool  tmp
backups  cache  crash  lib  local  lock  log  mail  metrics  opt  run  spool  tmp
ls: cannot access /hbtn: No such file or directory
$ ls /var && ls /var && ls /var && ls /hbtn && ls /hbtn
backups  cache  crash  lib  local  lock  log  mail  metrics  opt  run  spool  tmp
backups  cache  crash  lib  local  lock  log  mail  metrics  opt  run  spool  tmp
backups  cache  crash  lib  local  lock  log  mail  metrics  opt  run  spool  tmp
ls: cannot access /hbtn: No such file or directory
$
$ ls /var || ls /var
backups  cache  crash  lib  local  lock  log  mail  metrics  opt  run  spool  tmp
$ ls /hbtn || ls /var
ls: cannot access /hbtn: No such file or directory
backups  cache  crash  lib  local  lock  log  mail  metrics  opt  run  spool  tmp
$ ls /hbtn || ls /hbtn || ls /hbtn || ls /var
ls: cannot access /hbtn: No such file or directory
ls: cannot access /hbtn: No such file or directory
ls: cannot access /hbtn: No such file or directory
backups  cache  crash  lib  local  lock  log  mail  metrics  opt  run  spool  tmp
$ ls /hbtn || ls /hbtn || ls /hbtn || ls /var || ls /var
ls: cannot access /hbtn: No such file or directory
ls: cannot access /hbtn: No such file or directory
ls: cannot access /hbtn: No such file or directory
backups  cache  crash  lib  local  lock  log  mail  metrics  opt  run  spool  tmp
$