Combine commands

Declare successive or conditional sets of commands.

Successive commands

Generally, successive commands are executed in separate statements.

For instance:

echo "Some text"
echo "Some more text"

However, the symbol ; can be used to combine multiple commands in a single statement using the syntax command1; command2.

For instance:

echo "Some text"; echo "Some more text"

The statements are executed in order, from left to right.

While there is no major preference toward either syntax, a noticeable difference between the two approaches is that:

Separate statements visibly separate the output of the two commands. A new prompt is visible for each new command, marking the end of the output for one command and the start of the output for the next command.
Commands combined into a single statement do not demarcate the output of consecutive commands.

Commands can be combined logically, to conditionally execute later commands, depending on the successful completion of earlier commands.

The operator && can be used to execute a command only if the previous command completed succesfully, using the syntax command1 && command2.

The example below illustrates the two scenarios, in which the first command either completes successfully (first) or fails (second):

which echo && echo "Some text"
ls missing && echo "Some more text"

Conversely, the operator || cab be used to execute a command only if the previous command fails.

which echo || echo "Some text"
ls missing || echo "Some more text"