CustomShell

Small Unix-like shell in C.

Main Features

1. Batch mode: run shell with a script file argument.
2. Logical operators: short-circuit execution for && and ||.
3. Aliases: define, override, recursive expansion, loop protection.
4. History navigation: Up/Down arrows recall previous/next commands.

Other supported behavior:

1. cd, PWD/OLDPWD, jobs, pipes, redirection, background jobs, Ctrl+C/Ctrl+D handling.

Requirements

1. Linux environment (WSL recommended on Windows)
2. gcc, make, python3

Optional:

1. valgrind

Setup And Build

If you are in Windows PowerShell:

wsl
cd /mnt/d/Desktop/CustomShell\ -\ Copy
make -B

If you are already inside WSL terminal, do not type wsl again:

cd /mnt/d/Desktop/CustomShell\ -\ Copy
make -B

Run shell:

./bin/customShell

Run batch mode:

./bin/customShell /path/to/script.txt

Manual Tests

Batch mode

cat >/tmp/batch_test.txt <<"EOF"
echo one

echo two
echo three
EOF
./bin/customShell /tmp/batch_test.txt

Expected: prints one, two, three and exits.

Logical operators

shell208> true && echo AND_OK
shell208> false && echo SHOULD_NOT_PRINT
shell208> true || echo SHOULD_NOT_PRINT
shell208> false || echo OR_OK
shell208> false && echo NOPE || echo Done

Expected: AND_OK, OR_OK, Done; no SHOULD_NOT_PRINT, no NOPE.

Aliases

shell208> alias l='echo LS -l'
shell208> l -a
shell208> alias a='b'
shell208> alias b='a'
shell208> a

Expected: LS -l -a is printed; alias loop is detected and shell does not hang.

CD and env vars

shell208> env | grep PWD
shell208> cd /tmp
shell208> env | grep PWD
shell208> cd -

Expected: PWD and OLDPWD update correctly.

Ctrl+C and background job

shell208> sleep 5
(press Ctrl+C)
shell208> sleep 3 &
shell208> jobs
shell208> sleep 4
shell208> jobs

Expected: foreground sleep is interrupted; background sleep shows Running then Done.

Command history (Up/Down arrows)

shell208> echo first
shell208> echo second
(press Up) -> shows: echo second
(press Up) -> shows: echo first
(press Down) -> shows: echo second

Expected: Up/Down cycles command history without retyping.

Automated Tests

Run all test files:

python3 tests/python/test_all.py

Or discovery mode:

python3 -m unittest discover -s tests/python -p "test_*.py" -v

Run each feature test file:

1. Batch mode: python3 tests/python/test_batch_mode.py
2. Logical operators: python3 tests/python/test_logical_operations.py
3. Aliases: python3 tests/python/test_aliases.py
4. CD, PWD, OLDPWD: python3 tests/python/test_cd_pwd_oldpwd.py
5. Ctrl+C behavior: python3 tests/python/test_ctrl_c.py
6. Background jobs: python3 tests/python/test_background_jobs.py

Clean

make clean