find command with exec

cola · 06-01-2010, 11:41 AM

Code:

find /var/ftp/mp3 -name "*.mp3" -type f -exec chmod 644 {} \;

Why is "\" used?

cola · 06-01-2010, 11:45 AM

And what's the difference with this:

Code:

find /var/ftp/mp3 -name "*.mp3" -type f -exec chmod 644 '{}' \;

crts · 06-01-2010, 12:35 PM

Hi,

the single quotes and the backslash are used to protect the braces and the semicolon from shell expansion. See the man and info pages for more info on this.

catkin · 06-01-2010, 01:01 PM

Quote:

Originally Posted by crts

the single quotes and the backslash are used to protect the braces and the semicolon from shell expansion. See the man and info pages for more info on this.

More specifically the braces and semicolon are shell metacharacters as listed here. The special meaning of a metacharacter is removed when it is "escaped" (by putting a "\" in front of it) or enclosed in single quotes.

The ";" is used to separate lists of commands as explained here. In practice it is not much used because a line end does equally well.

The "{ }" is used to group commands as explained here. When it is empty -- as used in find commands -- it does not need to be escaped or quoted.

Tinkster · 06-01-2010, 01:21 PM

Quote:

Originally Posted by catkin

The ";" is used to separate lists of commands as explained here. In practice it is not much used because a line end does equally well.

Umm ... in this case (the escaped version) it's part of the
find command. It terminates the -exec ... and in that context
it's not only frequently used, it's indispensable.

Cheers,
Tink

vikas027 · 06-01-2010, 01:25 PM

Quote:

Originally Posted by catkin

More specifically the braces and semicolon are shell metacharacters as listed here. The special meaning of a metacharacter is removed when it is "escaped" (by putting a "\" in front of it) or enclosed in single quotes.

The ";" is used to separate lists of commands as explained here. In practice it is not much used because a line end does equally well.

The "{ }" is used to group commands as explained here. When it is empty -- as used in find commands -- it does not need to be escaped or quoted.

Good information.