问题
I have begun to combine different commands in the linux terminal. I am wondering why the backslash and semicolon are required for a command such as:
find ./ -name \'blabla\' -exec cp {} ./test \\;
when a simple cp command is simply:
cp randomfile ./test
without the \\;
Are they to clearly indicate the end of a command, or is it simply required in the documentation? What is the underlying principle?
Thank you!
回答1:
The backslash before the semicolon is used, because ; is one of list operators (or &&, ||) for separating shell commands. In example:
command1; command2
The find utility is using ; or + to terminate the shell commands invoked by -exec.
So to avoid special shell characters from interpretation, they need to be escaped with a backslash to remove any special meaning for the next character read and for line continuation.
Therefore the following example syntax is allowed for find command:
find . -exec echo {} \;
find . -exec echo {} ';'
find . -exec echo {} ";"
find . -exec echo {} \+
find . -exec echo {} +
See also:
- Using semicolon (;) vs plus (+) with exec in find
- Simple unix command, what is the {} and \; for
回答2:
from "man find":
All following arguments to find are taken to be arguments to the command until an argument consisting of ';' is encountered.
find needs to know when the arguments of exec are terminated. It is natural to terminate a shell command with ; because also the shell uses this character. For the very same reason such a character must be escaped when inserted through the shell.
来源：https://stackoverflow.com/questions/20913198/why-are-the-backslash-and-semicolon-required-with-the-find-commands-exec-optio