Grouping commands [Bash Hackers Wiki]

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====== Grouping commands ======

===== Synopsis =====
<code>{ <LIST>; }</code>

<code>
{
<LIST>
}
</code>

===== Description =====

The [[syntax:basicgrammar#lists|list]] ''<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 ''<LIST>'' 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:
<code>
{
  echo "PASSWD follows"
  cat /etc/passwd
  echo
  echo "GROUPS follows"
  cat /etc/group
} >output.txt
</code>

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:
<code>
print_help() {
  echo "Options:"
  echo "-h           This help text"
  echo "-f FILE      Use config file FILE"
  echo "-u USER      Run as user USER"
}
</code>

===== 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]]