Bash 4 introduced new terminators like ;;& to test the next pattern and ;& to execute the next list of commands. It added coprocesses to run processes in the background and communicate via file descriptors. Other new features included the mapfile command to read files into arrays, case modification in parameter substitution, declaring associative arrays, brace expansion, substring extraction, globstar to match directories recursively, $BASHPID to get the process ID, and improvements to read with options like -e, -t, and -i. Links to documentation and downloads were provided.

1. BASH 4
Amador Pahim
Analista de Redes
Universidade de Caxias do Sul
amador@pahim.org

2. --version
● Bash 3 - July 27, 2004
● Bash 4 - February 20, 2009

3. Case – new terminators
;;& testa próximo padrão
;& executa próxima lista de comandos

4. Coproc
coproc while read Entrada; do echo $Entrada; done
echo Teste >&${COPROC[1]}
read -u ${COPROC[0]} Saida
echo $Saida

5. Mapfile
mapfile array < file

6. Parameter substitution
case modification
echo ${var} - default
echo ${var^} - 1º uppercase
echo ${var^^} - All uppercase
echo ${var,} - 1º lowercase
echo ${var,,} - All lowercase

7. Declare
declare -A array
declare -l var
declare -c var

8. Brace expansion
echo {00..10..2}
echo {100..50..10}

9. Substring
echo ${@:0}

10. **
shopt -s globstar
echo **

11. $BASHPID
echo $BASHPID

12. read
read -e -t 3 -i default var

13. Links
http://www.gnu.org/software/bash/
ftp://ftp.gnu.org/gnu/bash/
http://br.gnome.org/TWikiBar/