# Check if Bash is installed
which bash
/bin/bash
# Check Bash version
bash --version
GNU bash, version 5.1.16(1)-release (x86_64-pc-linux-gnu)
# Check current shell
echo $SHELL
/bin/bash
# Check available shells
cat /etc/shells
```Bash (Bourne Again Shell) é um shell Unix e linguagem de comando escrito por Brian Fox para o Projeto GNU como um substituto de software livre para o Bourne Shell. Lançado pela primeira vez em 1989, o Bash tornou-se o shell padrão na maioria das distribuições Linux e é um dos shells mais utilizados no ecossistema Unix/Linux. Ele combina os recursos do shell Bourne original com funcionalidades adicionais, incluindo conclusão de comandos, histórico de comandos e recursos de script aprimorados.
## Instalação e Configuração
### Verificando a Instalação do Bash
```bash
# Set Bash as default shell for current user
chsh -s /bin/bash
# Set Bash as default shell for specific user (as root)
sudo chsh -s /bin/bash username
# Verify shell change
echo $SHELL
Definindo Bash como Shell Padrão
# Ubuntu/Debian
sudo apt update && sudo apt install bash
# CentOS/RHEL/Fedora
sudo dnf install bash
# macOS (using Homebrew for latest version)
brew install bash
# Arch Linux
sudo pacman -S bash
# FreeBSD
pkg install bash
Instalação do Bash em Diferentes Sistemas
# Basic command structure
command [options] [arguments]
# Examples
ls -la /home
cp file1.txt file2.txt
grep -r "pattern" /path/to/search
Sintaxe Básica e Comandos do Bash
Estrutura de Comandos
# Variable assignment (no spaces around =)
name="John Doe"
age=30
path="/home/user"
# Using variables
echo $name
echo $\\\\{name\\\\}
echo "Hello, $name"
# Environment variables
export PATH="/usr/local/bin:$PATH"
export EDITOR="vim"
# Special variables
echo $0 # Script name
echo $1 # First argument
echo $# # Number of arguments
echo $@ # All arguments
echo $ # Process ID
echo $? # Exit status of last command
Variáveis e Ambiente
# Using $() (preferred)
current_date=$(date)
file_count=$(ls|wc -l)
user_home=$(eval echo ~$USER)
# Using backticks (legacy)
current_date=`date`
file_count=`ls|wc -l`
# Nested command substitution
echo "Today is $(date +%A), $(date +%B) $(date +%d)"
Substituição de Comandos
# Single quotes (literal)
echo 'The variable $HOME is not expanded'
# Double quotes (variable expansion)
echo "Your home directory is $HOME"
# Escaping special characters
echo "The price is \$10"
echo "Use \"quotes\" inside quotes"
# Here documents
cat << EOF
This is a multi-line
text block that can contain
variables like $HOME
EOF
# Here strings
grep "pattern" <<< "$variable"
Citação e Escape
# Change directory
cd /path/to/directory
cd ~ # Home directory
cd - # Previous directory
cd .. # Parent directory
cd ../.. # Two levels up
# Print working directory
pwd
# Directory stack operations
pushd /path/to/dir # Push directory onto stack
popd # Pop directory from stack
dirs # Show directory stack
Operações de Arquivos e Navegação
Navegação de Diretórios
# Basic listing
ls
ls -l # Long format
ls -la # Long format with hidden files
ls -lh # Human readable sizes
ls -lt # Sort by modification time
ls -lS # Sort by size
ls -lR # Recursive listing
# Advanced listing options
ls -la --color=auto # Colored output
ls -la --time-style=full-iso # ISO time format
ls -la --group-directories-first # Directories first
Listagem de Arquivos e Diretórios
# Create files
touch file.txt
touch file1.txt file2.txt file3.txt
# Copy files and directories
cp source.txt destination.txt
cp -r source_dir/ destination_dir/
cp -p file.txt backup.txt # Preserve attributes
cp -u source.txt dest.txt # Update only if newer
# Move and rename
mv old_name.txt new_name.txt
mv file.txt /path/to/destination/
mv *.txt /path/to/directory/
# Remove files and directories
rm file.txt
rm -f file.txt # Force removal
rm -r directory/ # Recursive removal
rm -rf directory/ # Force recursive removal
rm -i *.txt # Interactive removal
# Create directories
mkdir directory_name
mkdir -p path/to/nested/directory
mkdir -m 755 directory_name # With specific permissions
Operações de Arquivos
# Change permissions
chmod 755 file.txt
chmod u+x script.sh # Add execute for user
chmod g-w file.txt # Remove write for group
chmod o=r file.txt # Set read-only for others
chmod -R 644 directory/ # Recursive permission change
# Change ownership
chown user:group file.txt
chown -R user:group directory/
chgrp group file.txt # Change group only
# View permissions
ls -l file.txt
stat file.txt # Detailed file information
Permissões e Propriedade de Arquivos
# View file contents
cat file.txt # Display entire file
less file.txt # Paginated view
more file.txt # Simple paginated view
head file.txt # First 10 lines
head -n 20 file.txt # First 20 lines
tail file.txt # Last 10 lines
tail -n 20 file.txt # Last 20 lines
tail -f file.txt # Follow file changes
# File comparison
diff file1.txt file2.txt
diff -u file1.txt file2.txt # Unified format
cmp file1.txt file2.txt # Binary comparison
Processamento e Manipulação de Texto
Operações de Conteúdo de Arquivos
# grep - pattern searching
grep "pattern" file.txt
grep -i "pattern" file.txt # Case insensitive
grep -r "pattern" directory/ # Recursive search
grep -n "pattern" file.txt # Show line numbers
grep -v "pattern" file.txt # Invert match
grep -E "pattern1|pattern2" file.txt # Extended regex
# Advanced grep options
grep -A 3 "pattern" file.txt # Show 3 lines after match
grep -B 3 "pattern" file.txt # Show 3 lines before match
grep -C 3 "pattern" file.txt # Show 3 lines around match
grep -l "pattern" *.txt # Show only filenames
grep -c "pattern" file.txt # Count matches
Busca e Filtragem de Texto
# sed - stream editor
sed 's/old/new/' file.txt # Replace first occurrence
sed 's/old/new/g' file.txt # Replace all occurrences
sed '1,5s/old/new/g' file.txt # Replace in lines 1-5
sed '/pattern/d' file.txt # Delete lines matching pattern
sed -n '1,10p' file.txt # Print lines 1-10
# awk - pattern scanning and processing
awk '\\\\{print $1\\\\}' file.txt # Print first column
awk '\\\\{print $NF\\\\}' file.txt # Print last column
awk '/pattern/ \\\\{print $0\\\\}' file.txt # Print lines matching pattern
awk -F: '\\\\{print $1\\\\}' /etc/passwd # Use : as field separator
awk '\\\\{sum += $1\\\\} END \\\\{print sum\\\\}' file.txt # Sum first column
# cut - extract columns
cut -d: -f1 /etc/passwd # Extract first field
cut -c1-10 file.txt # Extract characters 1-10
cut -f2,4 file.txt # Extract fields 2 and 4
# sort and uniq
sort file.txt # Sort lines
sort -n file.txt # Numeric sort
sort -r file.txt # Reverse sort
sort -k2 file.txt # Sort by second field
uniq file.txt # Remove duplicate lines
sort file.txt|uniq -c # Count occurrences
Ferramentas de Processamento de Texto
# Output redirection
command > file.txt # Redirect stdout to file (overwrite)
command >> file.txt # Redirect stdout to file (append)
command 2> error.log # Redirect stderr to file
command 2>> error.log # Redirect stderr to file (append)
command &> output.log # Redirect both stdout and stderr
command > output.log 2>&1 # Redirect both stdout and stderr
# Input redirection
command < input.txt # Read input from file
command << EOF # Here document
line 1
line 2
EOF
# Advanced redirection
command 3> file.txt # Redirect to file descriptor 3
exec 3> file.txt # Open file descriptor 3
echo "text" >&3 # Write to file descriptor 3
exec 3>&- # Close file descriptor 3
Redirecionamento de Entrada/Saída e Pipes
Operadores de Redirecionamento
# Basic pipes
ls -l|grep "txt" # List files and filter for .txt
ps aux|grep "process_name" # Show processes and filter
cat file.txt|sort|uniq # Sort and remove duplicates
# Complex pipe chains
cat /var/log/access.log|grep "404"|awk '\\\\{print $1\\\\}'|sort|uniq -c|sort -nr
find . -name "*.log"|xargs grep "ERROR"|cut -d: -f1|sort|uniq
# Tee command (split output)
command|tee file.txt # Write to file and stdout
command|tee -a file.txt # Append to file and stdout
Pipes e Encadeamento de Comandos
# Background and foreground jobs
command & # Run command in background
jobs # List active jobs
fg %1 # Bring job 1 to foreground
bg %1 # Send job 1 to background
kill %1 # Kill job 1
# Process control signals
Ctrl+C # Interrupt (SIGINT)
Ctrl+Z # Suspend (SIGTSTP)
Ctrl+\ # Quit (SIGQUIT)
Gerenciamento de Processos
Controle de Tarefas
# Process listing
ps # Show current processes
ps aux # Show all processes
ps -ef # Full format listing
pstree # Show process tree
top # Real-time process monitor
htop # Enhanced process monitor
# Process management
kill PID # Terminate process
kill -9 PID # Force kill process
killall process_name # Kill all processes by name
pkill pattern # Kill processes matching pattern
nohup command & # Run command immune to hangups
#!/bin/bash
# Script description and metadata
# Author: Your Name
# Date: YYYY-MM-DD
# Version: 1.0
# Script content starts here
echo "Hello, World!"
```### Variáveis e Tipos de Dados
```bash
# String variables
name="John Doe"
message='Hello, World!'
multiline="This is a
multi-line string"
# Numeric variables
number=42
pi=3.14159
# Arrays
fruits=("apple" "banana" "orange")
numbers=(1 2 3 4 5)
# Associative arrays (Bash 4+)
declare -A colors
colors[red]="#FF0000"
colors[green]="#00FF00"
colors[blue]="#0000FF"
# Array operations
echo $\\\\{fruits[0]\\\\} # First element
echo $\\\\{fruits[@]\\\\} # All elements
echo $\\\\{#fruits[@]\\\\} # Array length
fruits+=("grape") # Append element
```### Declarações Condicionais
```bash
# if-then-else
if [ condition ]; then
echo "Condition is true"
elif [ other_condition ]; then
echo "Other condition is true"
else
echo "No condition is true"
fi
# Test conditions
if [ "$var" = "value" ]; then # String equality
if [ "$num" -eq 10 ]; then # Numeric equality
if [ "$num" -gt 5 ]; then # Greater than
if [ "$num" -lt 20 ]; then # Less than
if [ -f "file.txt" ]; then # File exists
if [ -d "directory" ]; then # Directory exists
if [ -r "file.txt" ]; then # File is readable
if [ -w "file.txt" ]; then # File is writable
if [ -x "script.sh" ]; then # File is executable
# Logical operators
if [ condition1 ] && [ condition2 ]; then # AND
if [ condition1 ]||[ condition2 ]; then # OR
if [ ! condition ]; then # NOT
# Case statement
case $variable in
pattern1)
echo "Matched pattern1"
;;
pattern2|pattern3)
echo "Matched pattern2 or pattern3"
;;
*)
echo "No pattern matched"
;;
esac
```### Loops
```bash
# for loop
for i in \\\\{1..10\\\\}; do
echo "Number: $i"
done
for file in *.txt; do
echo "Processing: $file"
done
for item in "$\\\\{array[@]\\\\}"; do
echo "Item: $item"
done
# C-style for loop
for ((i=1; i<=10; i++)); do
echo "Counter: $i"
done
# while loop
counter=1
while [ $counter -le 10 ]; do
echo "Counter: $counter"
((counter++))
done
# until loop
counter=1
until [ $counter -gt 10 ]; do
echo "Counter: $counter"
((counter++))
done
# Loop control
for i in \\\\{1..10\\\\}; do
if [ $i -eq 5 ]; then
continue # Skip iteration
fi
if [ $i -eq 8 ]; then
break # Exit loop
fi
echo $i
done
```### Funções
```bash
# Function definition
function greet() \\\\{
echo "Hello, $1!"
\\\\}
# Alternative syntax
greet() \\\\{
echo "Hello, $1!"
\\\\}
# Function with return value
calculate_sum() \\\\{
local num1=$1
local num2=$2
local sum=$((num1 + num2))
echo $sum
\\\\}
# Function with local variables
process_file() \\\\{
local filename=$1
local line_count=$(wc -l < "$filename")
echo "File $filename has $line_count lines"
\\\\}
# Function usage
greet "World"
result=$(calculate_sum 5 3)
echo "Sum: $result"
```## Recursos Avançados do Bash
```bash
# Basic parameter expansion
echo $\\\\{variable\\\\}
echo $\\\\{variable:-default\\\\} # Use default if unset
echo $\\\\{variable:=default\\\\} # Set default if unset
echo $\\\\{variable:+alternate\\\\} # Use alternate if set
echo $\\\\{variable:?error\\\\} # Error if unset
# String manipulation
string="Hello, World!"
echo $\\\\{string#Hello\\\\} # Remove shortest match from beginning
echo $\\\\{string##*/\\\\} # Remove longest match from beginning
echo $\\\\{string%World!\\\\} # Remove shortest match from end
echo $\\\\{string%%/*\\\\} # Remove longest match from end
echo $\\\\{string/Hello/Hi\\\\} # Replace first occurrence
echo $\\\\{string//l/L\\\\} # Replace all occurrences
# Substring extraction
echo $\\\\{string:0:5\\\\} # Extract substring (position:length)
echo $\\\\{string:7\\\\} # Extract from position to end
echo $\\\\{#string\\\\} # String length
```### Expansão de Parâmetros
```bash
# Arithmetic expansion
result=$((5 + 3))
result=$((10 * 2))
result=$((20 / 4))
result=$((17 % 5)) # Modulo
# Increment/decrement
((counter++))
((counter--))
((counter += 5))
((counter -= 3))
# Arithmetic with variables
num1=10
num2=5
sum=$((num1 + num2))
product=$((num1 * num2))
# Floating point arithmetic (using bc)
result=$(echo "scale=2; 10/3"|bc)
result=$(echo "scale=4; sqrt(16)"|bc -l)
```### Operações Aritméticas
```bash
# Exit on error
set -e # Exit on any error
set -u # Exit on undefined variable
set -o pipefail # Exit on pipe failure
# Error handling in scripts
command||\\\\{
echo "Command failed"
exit 1
\\\\}
# Trap signals
trap 'echo "Script interrupted"; exit 1' INT TERM
trap 'cleanup_function' EXIT
# Function error handling
safe_command() \\\\{
if ! command_that_might_fail; then
echo "Error: Command failed" >&2
return 1
fi
\\\\}
```### Tratamento de Erros
```bash
# System-wide configuration
/etc/bash.bashrc # System-wide bashrc
/etc/profile # System-wide profile
# User-specific configuration
~/.bashrc # User's bashrc
~/.bash_profile # User's profile
~/.bash_login # Login shell configuration
~/.profile # POSIX shell profile
~/.bash_logout # Logout script
```## Configuração e Personalização
```bash
# ~/.bashrc example configuration
# Source global definitions
if [ -f /etc/bashrc ]; then
. /etc/bashrc
fi
# User specific environment
export EDITOR="vim"
export BROWSER="firefox"
export PAGER="less"
# Custom PATH
export PATH="$HOME/bin:$HOME/.local/bin:$PATH"
# Aliases
alias ll='ls -alF'
alias la='ls -A'
alias l='ls -CF'
alias grep='grep --color=auto'
alias fgrep='fgrep --color=auto'
alias egrep='egrep --color=auto'
# Custom functions
mkcd() \\\\{
mkdir -p "$1" && cd "$1"
\\\\}
extract() \\\\{
if [ -f $1 ] ; then
case $1 in
*.tar.bz2) tar xjf $1 ;;
*.tar.gz) tar xzf $1 ;;
*.bz2) bunzip2 $1 ;;
*.rar) unrar e $1 ;;
*.gz) gunzip $1 ;;
*.tar) tar xf $1 ;;
*.tbz2) tar xjf $1 ;;
*.tgz) tar xzf $1 ;;
*.zip) unzip $1 ;;
*.Z) uncompress $1 ;;
*.7z) 7z x $1 ;;
*) echo "'$1' cannot be extracted via extract()" ;;
esac
else
echo "'$1' is not a valid file"
fi
\\\\}
# Prompt customization
PS1='\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ '
# History configuration
HISTSIZE=10000
HISTFILESIZE=20000
HISTCONTROL=ignoredups:ignorespace
shopt -s histappend
# Shell options
shopt -s checkwinsize
shopt -s globstar
shopt -s cdspell
```### Arquivos de Configuração do Bash
```bash
# Set options
set -o vi # Vi editing mode
set -o emacs # Emacs editing mode (default)
set -o noclobber # Prevent file overwriting
set +o noclobber # Allow file overwriting
# Shopt options
shopt -s autocd # Auto cd to directory
shopt -s cdspell # Correct minor spelling errors
shopt -s checkwinsize # Update LINES and COLUMNS
shopt -s cmdhist # Save multi-line commands
shopt -s dotglob # Include hidden files in globbing
shopt -s expand_aliases # Expand aliases
shopt -s extglob # Extended globbing
shopt -s globstar # ** recursive globbing
shopt -s histappend # Append to history file
shopt -s nocaseglob # Case-insensitive globbing
```### Personalizando .bashrc
```bash
# Emacs mode (default)
Ctrl+A # Beginning of line
Ctrl+E # End of line
Ctrl+B # Back one character
Ctrl+F # Forward one character
Alt+B # Back one word
Alt+F # Forward one word
Ctrl+D # Delete character
Ctrl+H # Backspace
Ctrl+K # Kill to end of line
Ctrl+U # Kill to beginning of line
Ctrl+W # Kill previous word
Alt+D # Kill next word
Ctrl+Y # Yank (paste)
Ctrl+T # Transpose characters
Alt+T # Transpose words
# Vi mode
set -o vi
Esc # Enter command mode
i # Insert mode
a # Append mode
A # Append at end of line
I # Insert at beginning of line
```### Opções e Configurações do Bash
```bash
# History commands
history # Show command history
history 10 # Show last 10 commands
history -c # Clear history
history -d 5 # Delete history entry 5
# History expansion
!! # Previous command
!n # Command number n
!string # Last command starting with string
!?string # Last command containing string
^old^new # Replace old with new in previous command
# History search
Ctrl+R # Reverse search
Ctrl+S # Forward search
Ctrl+G # Cancel search
# History configuration
export HISTSIZE=10000 # Commands in memory
export HISTFILESIZE=20000 # Commands in file
export HISTCONTROL=ignoredups # Ignore duplicates
export HISTIGNORE="ls:ll:cd:pwd:bg:fg:history" # Ignore commands
export HISTTIMEFORMAT="%F %T " # Add timestamps
```## Edição de Linha de Comando e Histórico
```bash
# Debug modes
bash -x script.sh # Execute with trace
bash -n script.sh # Check syntax without execution
bash -v script.sh # Verbose mode
# Debug options in script
set -x # Enable trace
set +x # Disable trace
set -v # Enable verbose
set +v # Disable verbose
# Conditional debugging
if [ "$DEBUG" = "1" ]; then
set -x
fi
# Debug function
debug() \\\\{
if [ "$DEBUG" = "1" ]; then
echo "DEBUG: $*" >&2
fi
\\\\}
```### Edição de Linha de Comando
```bash
# Check command success
if command; then
echo "Command succeeded"
else
echo "Command failed"
fi
# Check exit status
command
if [ $? -eq 0 ]; then
echo "Success"
else
echo "Failed with exit code $?"
fi
# Validate input
if [ $# -ne 2 ]; then
echo "Usage: $0 <arg1> <arg2>"
exit 1
fi
# Check file existence
if [ ! -f "$filename" ]; then
echo "Error: File $filename does not exist"
exit 1
fi
```### Gerenciamento de Histórico
```bash
# Time command execution
time command
time \\\\{ command1; command2; \\\\}
# Profile script execution
PS4='+ $(date "+%s.%N"): '
set -x
# Your commands here
set +x
# Memory usage
/usr/bin/time -v command
# Disk usage
du -sh directory/
df -h
```## Depuração e Solução de Problemas
```bash
# Use full paths for commands
/bin/ls instead of ls
/usr/bin/find instead of find
# Validate input
case "$input" in
[a-zA-Z0-9]*)
# Valid input
;;
*)
echo "Invalid input"
exit 1
;;
esac
# Quote variables
rm "$filename" # Correct
rm $filename # Dangerous
# Use arrays for file lists
files=( *.txt )
for file in "$\\\\{files[@]\\\\}"; do
process "$file"
done
```### Depurando Scripts
```bash
# Use built-in commands when possible
[[ condition ]] # Instead of [ condition ]
(( arithmetic )) # Instead of [ arithmetic ]
# Avoid unnecessary subshells
var=$(cat file) # Subshell
var=$(<file) # Built-in
# Use parameter expansion
$\\\\{var#pattern\\\\} # Instead of sed/awk for simple operations
$\\\\{var%pattern\\\\}
$\\\\{var/pattern/replacement\\\\}
# Efficient loops
while IFS= read -r line; do # Read file line by line
process "$line"
done < file.txt
```### Verificação de Erros
```bash
# Use functions for repeated code
log_message() \\\\{
echo "[$(date '+%Y-%m-%d %H:%M:%S')] $*" >&2
\\\\}
# Separate configuration
CONFIG_FILE="$\\\\{HOME\\\\}/.myapp.conf"
if [ -f "$CONFIG_FILE" ]; then
source "$CONFIG_FILE"
fi
# Use meaningful variable names
user_count=10 # Good
uc=10 # Poor
# Comment complex logic
# Calculate the number of days between two dates
start_date=$(date -d "$1" +%s)
end_date=$(date -d "$2" +%s)
days=$(( (end_date - start_date) / 86400 ))
```### Monitoramento de Desempenho
