Hacking Cafe

Hacking Cafe is a Unix/Linux and Bash simulator in the browser. This project is a continuation of Fake Linux Terminal. The source code is released under the GNU AGPL license and can be found on GitHub.

Bash syntax

Implemented bash syntax:

variables
: and . shortcuts (for true and source commands)
subshells $(...), (...), and `...`
double-quote expressions
variable assignments
arrays
pipes
redirects (>, >>, and <)
JavaScript programs using web workers
Bash scripts
custom interpreters with shebang
glob patterns
for
if
&&/||
while, until
while read line
case/esac
read -p "continue? (y/n) "

Functions

name() { ...; } and function name { ...; }
positional parameters $1, $#, $*, $@ scoped to the call
visible in subshells, pipelines and command substitution
redirects on the call, f > file
return
shift

Default variables

$PS1 - controlling the prompt
$PATH - list of paths separated by : where executables are searched
$IFS - controlling splitting text into fields
$? - exit code from last command
$PWD - current working directory
$0-$9 - arguments to bash scripts
$@ / $* / $# - all args and length of args

Variable expansions

${DATABASE_URL:="localhost"}
USER_ID=${1:?"Error, arg missing!"}
${VAR:-default}
${VAR-default}
${var+alternative}
${var:+alternative}
${VAR/x/y} - replace
${VAR//x/y} - replace all
${TEXT:4} ${TEXT:0:4} - slice
${FILE%.*} - remove trailing non-greedy
${PATH%%:*} remove trailing greedy
${PATH##*/} - remove greedy before
EXTENSION=${FILE#*.} - remove before
${NAME^} - camel case
${NAME^^} - upper case
LEN=${#NAME} - string length
${!POINTER} - indirect variable

Build commands

Some of them should be in the /bin directory.

cat - concatenates the files or reads from stdin
grep - global regex print
echo - prints to the stdout
printf - similar to echo
kill - kill the process
exit - exit the bash script
ps - list processes (bash is always 0)
rm - remove file
cd - change directory
mkdir - make directory
pwd - print working directory
ls - list directory
adduser (create home directory, but there is no login yet)
source - includes the bash script in the current shell
chmod - change permissions
ln - create symlinks (hard links not supported)
read - reads a line from stdin and splits it using $IFS.
test - various checks on files and compares values
pushd/popd - stack-based navigation
dirs - print current stack
export - export variable (so it can be accessed in a subprocess)
unset - remove variable

Default file system

|-- bin
|   |-- cowsay
|   |-- false
|   |-- figlet
|   |-- highlight
|   |-- js
|   |-- python
|   |-- sleep
|   |-- true
|   `-- vi
|-- etc
|   |-- bashrc
|   `-- passwd
`-- root

Custom Commands

fetch (neofetch)
rfc (RFC viewer using less)
less
record - save commands in URL hash
credits
help