Linux file to determine whether there is a command of

The presence of file output yes, otherwise output no.

shell terminal to execute:

[ -f hello.txt ] && echo yes || echo no

• -f 文件名字True file exists.
• Execution [ -f hello.txt ]is true is executed echo yes, or the statement because the ||presence of echo nono longer perform.
• In particular, where the logic and the logic or worthy of careful consideration.