~$ echo one && echo two
This runs the 2. command only if the first command succeeds.
~$ echo one ; echo two
This always runs the 2. command.
~$ echo one || echo two
This runs the 2. command only if the first command fails.
A command is considered successful if its exit code is 0, and considered failed if
its exit code is != 0.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…