About the control operators & and ;, from POSIX 2013:For asynchronous lists, the format for running a command in the background is:command1 & [command2 & ... ]For sequential lists, the format for executing commands sequentially shall be:command1 [; command2] ...Is & unary or binary? Is ; unary or binary?& and ; look like binary, which operate the commands before andafter them, and indicate that the execution order between the twocommands is concurrent or sequential.& looks like unary, because every command in an asynchronous listis followed by a &.; doesn't look like unary, because the last command in asequential list doesn't need a following ;.Note: operators operates on operands. Depending on the number ofoperands, we can say an operator is unary, binary, .... Controloperators, if I understand correctly, are operators on commands.In a mixed list of & and ;, what is the execution order betweenthe component commands? What does each of & and ; mean to thecomponent commands?For example, in Bash$ echo 1 ; echo 2 & echo 3; echo 4 & echo 51[1] 1108932[2] 1109054[1]-  Done                    echo 2[2]+  Done                    echo 4$ echo 1 ; echo 2 & echo 3; echo 4 & echo 5 ; echo 6 &1[1] 111003[2] 111015[3] 11102642[1]   Done                    echo 2[2]-  Done                    echo 4[3]+  Done                    echo 6
Are & and ; unary or binary operators?
bash;shell;posix