Quick Start

Launching Minishell

After building Minishell, start the shell from your build directory:

./minishell

You’ll see the Minishell prompt, which displays your username and current directory:

minishell>

The prompt is generated by the ft_print_user() function and updates dynamically based on your current directory.

Your First Commands

Try a Simple Built-in Command

Start with the pwd command to print your current working directory:

minishell> pwd
/home/user/minishell

The implementation from builtins.c uses the getcwd() system call:

void pwd(int argc)
{
    char *pwd;
    
    if (argc > 1)
    {
        printf("pwd: too many arguments\n");
        return ;
    }
    pwd = getcwd(NULL, 0);
    printf("%s\n", pwd);
    free(pwd);
    g_status = 0;
}

Display Text with Echo

Use the echo command to print text:

minishell> echo Hello, Minishell!
Hello, Minishell!

Try the -n flag to suppress the newline:

minishell> echo -n No newline here
No newline hereminishell>

The echo built-in supports the -n flag just like bash, implemented in builtins.c:87-106.

Navigate Directories

Change directories using cd:

minishell> cd /tmp
minishell> pwd
/tmp

minishell> cd
minishell> pwd
/home/user

Without arguments, cd takes you to your home directory:

void cd(int argc, char *av)
{
    char *path;
    
    if (argc == 1)
        path = getenv("HOME");
    else
        path = av;
    if (chdir(path) == -1)
    {
        g_status = 1;
        perror("cd");
        return ;
    }
    g_status = 0;
}

List Files with External Commands

Minishell executes external programs by searching the PATH:

minishell> ls -la
total 248
drwxr-xr-x  4 user user   4096 Mar  7 12:00 .
drwxr-xr-x 28 user user   4096 Mar  6 10:30 ..
-rw-r--r--  1 user user   2140 Mar  7 11:00 main.c
-rwxr-xr-x  1 user user  45832 Mar  7 12:00 minishell

Try other common commands:

minishell> cat minishell.h
minishell> grep "typedef" minishell.h
minishell> wc -l *.c

Working with Environment Variables

Viewing Environment Variables

minishell> env
PATH=/usr/local/bin:/usr/bin:/bin
HOME=/home/user
USER=user
SHELL=/bin/bash
...

Variable Expansion

Minishell supports environment variable expansion using the $ prefix:

minishell> export GREETING=Hello
minishell> echo $GREETING World
Hello World

The expansion is handled by the vars() function in env_parsed.c:

char *vars(char *commands, t_prompt *env, int i, int x)
{
    // Parses and expands $VAR in command strings
    // Handles special cases like $? for exit status
}

Special Variables

Check the exit status of the last command:

minishell> ls /nonexistent
ls: cannot access '/nonexistent': No such file or directory

minishell> echo $?
2

minishell> echo success
success

minishell> echo $?
0

Remove Variables

Use unset to remove environment variables:

minishell> export TEMP_VAR=test
minishell> echo $TEMP_VAR
test

minishell> unset TEMP_VAR
minishell> echo $TEMP_VAR

Your First Pipeline

Pipelines connect the output of one command to the input of another using the | operator.

Basic Pipe Example

minishell> ls -l | grep minishell
-rwxr-xr-x 1 user user 45832 Mar  7 12:00 minishell
-rw-r--r-- 1 user user  4567 Mar  7 11:00 minishell.h

This pipes the output of ls -l into grep, which filters for lines containing “minishell”.

Multi-Command Pipeline

Chain multiple commands together:

minishell> cat *.c | grep "include" | wc -l
42

This pipeline:

Concatenates all .c files (cat *.c)
Filters for lines with “include” (grep "include")
Counts the matching lines (wc -l)

How Pipes Work

Minishell creates separate processes for each command and connects them:

// From ft_execute_commands.c - Pipeline execution
void excecute_pipe_sequence(t_mini *data, int pipefd[2])
{
    int aux[2];
    
    aux[0] = -1;
    aux[1] = -1;
    while (data->nodes[++aux[0]])
    {
        if (pipe(pipefd) == -1)
            return ;
        data->nodes[aux[0]]->n_pid = fork();
        if (data->nodes[aux[0]]->n_pid == 0
            && data->nodes[aux[0]]->is_set == 1)
            child_process(data, data->nodes[aux[0]], aux, pipefd);
        // Parent process continues...
    }
}

Input and Output Redirection

Output Redirection

Redirect command output to a file:

minishell> echo "Hello" > output.txt
minishell> cat output.txt
Hello

minishell> ls -l > filelist.txt

Input Redirection

Read command input from a file:

minishell> echo "apple\nbanana\ncherry" > fruits.txt
minishell> wc -l < fruits.txt
3

Heredoc (`<<`)

Provide multi-line input interactively:

minishell> cat << EOF
> This is line 1
> This is line 2
> This is line 3
> EOF
This is line 1
This is line 2
This is line 3

The heredoc is handled by the check_heredoc() function:

void check_heredoc(char *limit, int *infile)
{
    int fd;
    char *line;
    
    fd = open(TEMP_FILE, O_CREAT | O_WRONLY | O_TRUNC, 0644);
    while (1)
    {
        line = readline(">");
        if (!line || (!ft_strncmp(line, limit, ft_strlen(limit))))
            break ;
        write(fd, line, strlen(line));
        write(fd, "\n", 1);
    }
    close(fd);
    *infile = open(TEMP_FILE, O_RDONLY);
}

Combining Redirections

You can combine multiple redirections:

minishell> cat < input.txt > output.txt
minishell> grep "error" < logfile.txt >> errors.txt
minishell> cat << END | grep "test" > results.txt
> test line 1
> other line
> test line 2
> END

Quote Handling

Minishell properly handles single and double quotes:

minishell> echo 'Hello $USER'
Hello $USER
# Variables NOT expanded in single quotes

Quotes are removed before command execution by the remove_quotes() function in parse_imput.c.

Signal Handling

Minishell responds to keyboard signals:

Ctrl+C (SIGINT): Cancels current command and displays a new prompt
Ctrl+D (EOF): Exits the shell when pressed on an empty line
*Ctrl+* (SIGQUIT): Ignored in interactive mode (unlike bash)

// From signals.c - Signal setup
void setup_signals(void)
{
    signal(SIGINT, handle_sigint);
    signal(SIGQUIT, SIG_IGN);
}

void handle_sigint(int sig)
{
    g_status = 130;
    write(1, "\n", 1);
    rl_on_new_line();
    rl_replace_line("", 0);
    rl_redisplay();
}

Exiting the Shell

There are three ways to exit Minishell:

minishell> exit
# Exits with status 0

minishell> exit 42
# Exits with status 42

Practical Examples

Example 1: File Processing Pipeline

minishell> cat employees.txt | grep "Engineer" | wc -l
15

Counts how many employees are engineers.

Example 2: Log Analysis

minishell> grep "ERROR" app.log > errors.txt
minishell> wc -l < errors.txt
27
minishell> cat errors.txt | head -5

Extracts errors from a log file and examines them.

Example 3: Environment Setup

minishell> export PROJECT_DIR=/home/user/project
minishell> export PATH=$PATH:$PROJECT_DIR/bin
minishell> cd $PROJECT_DIR
minishell> pwd
/home/user/project

Configures project-specific environment variables.

Example 4: Data Transformation

minishell> cat data.csv | cut -d',' -f2 | sort | uniq > unique_values.txt

Extracts the second column from a CSV, sorts it, and removes duplicates.

Command History

Minishell uses GNU Readline for command history:

Up Arrow: Navigate to previous commands
Down Arrow: Navigate to next commands
Ctrl+R: Search command history (if enabled)

History is managed automatically:

// From main.c - Adding to history
void enterdata(char *line, t_mini *data, int i)
{
    add_history(line);
    // Process command...
}

Common Pitfalls

Unclosed Quotes: Minishell detects unclosed quotes and reports syntax errors:

minishell> echo "hello
syntax error: unclosed quotes

Invalid Pipes: Empty pipe segments cause errors:

minishell> ls | | grep test
syntax error near unexpected token '|'

Redirection Errors: Missing filenames after redirection operators:

minishell> echo "test" >
syntax error near unexpected token 'newline'

Next Steps

Now that you understand the basics, explore more advanced features:

Built-in Commands

Detailed reference for all built-in commands

Pipelines

Advanced pipeline techniques

Redirections

Input and output redirection

Environment Variables

Managing and using environment variables

Get Started

User Guide

Technical Reference

Development

Launching Minishell

Your First Commands

Working with Environment Variables

Viewing Environment Variables

Variable Expansion

Special Variables

Remove Variables

Your First Pipeline

Basic Pipe Example

Multi-Command Pipeline

How Pipes Work

Input and Output Redirection

Output Redirection

Input Redirection

Heredoc (`<<`)

Combining Redirections

Quote Handling

Signal Handling

Exiting the Shell

Practical Examples

Example 1: File Processing Pipeline

Example 2: Log Analysis

Example 3: Environment Setup

Example 4: Data Transformation

Command History

Common Pitfalls

Next Steps

Built-in Commands

Pipelines

Redirections

Environment Variables

Build docs developers (and LLMs) love

Get Started

User Guide

Technical Reference

Development

​Launching Minishell

​Your First Commands

​Working with Environment Variables

​Viewing Environment Variables

​Variable Expansion

​Special Variables

​Remove Variables

​Your First Pipeline

​Basic Pipe Example

​Multi-Command Pipeline

​How Pipes Work

​Input and Output Redirection

​Output Redirection

​Input Redirection

​Heredoc (<<)

​Combining Redirections

​Quote Handling

​Signal Handling

​Exiting the Shell

​Practical Examples

​Example 1: File Processing Pipeline

​Example 2: Log Analysis

​Example 3: Environment Setup

​Example 4: Data Transformation

​Command History

​Common Pitfalls

​Next Steps

Built-in Commands

Pipelines

Redirections

Environment Variables

Build docs developers (and LLMs) love

Launching Minishell

Your First Commands

Working with Environment Variables

Viewing Environment Variables

Variable Expansion

Special Variables

Remove Variables

Your First Pipeline

Basic Pipe Example

Multi-Command Pipeline

How Pipes Work

Input and Output Redirection

Output Redirection

Input Redirection

Heredoc (`<<`)

Combining Redirections

Quote Handling

Signal Handling

Exiting the Shell

Practical Examples

Example 1: File Processing Pipeline

Example 2: Log Analysis

Example 3: Environment Setup

Example 4: Data Transformation

Command History

Common Pitfalls

Next Steps