====== Grouping commands ======
===== Synopsis =====
{ ; }
{
}
===== Description =====
The [[syntax:basicgrammar#lists|list]] '''' is simply executed in the **current** shell environment. The list must be terminated with a **newline** or **semicolon**. For parsing reasons, the curly braces must be separated from '''' by a **semicolon** and **blanks** if they're in the same line! ((Actually any properly terminated compound command will work without extra separator (also in some other shells), **example**: ''{ while sleep 1; do echo ZzZzzZ; done }'' is valid. But this is not documented, infact the documentation explicitly says that a semicolon or a newline must separate the enclosed list. -- thanks ''geirha'' at Freenode))((The main reason is the fact that in shell grammar, the curly braces are not control operators but reserved words -- TheBonsai))
This is known as a **group command**. The return status is the [[scripting:basics#exit_codes|exit status (exit code)]] of the list.
The input and output **filedescriptors** are cumulative:
{
echo "PASSWD follows"
cat /etc/passwd
echo
echo "GROUPS follows"
cat /etc/group
} >output.txt
This compound command also usually is the body of a [[syntax:basicgrammar#shell_function_definitions | function definition]], though not the only compound command that's valid there:
print_help() {
echo "Options:"
echo "-h This help text"
echo "-f FILE Use config file FILE"
echo "-u USER Run as user USER"
}
===== Examples =====
==== A Try-Catch block ====
try_catch() {
{ # Try-block:
eval "$@"
} ||
{ # Catch-block:
echo "An error occurred"
return -1
}
}
===== Portability considerations =====
===== See also =====
* [[syntax:ccmd:grouping_subshell | grouping commands in a subshell]]