what does the -@ mean when zipping a file in unix?

Question

I found this command online, but not sure what the -@ means.

find . -type f -mtime -29 -mtime +21 | zip -@ 061110_061201.zip

thanks all, i am using MobaXterm and for some reason it doesn't return anything when i do a "man zip". — clayton33, Sep 14 '15 at 15:38
If you don't have the zip utility installed, then man zip will not work as the manual pages will not be installed. — Burhan Khalid, Sep 15 '15 at 05:34

score 8 · Accepted Answer · edited Apr 13 '17 at 12:37

8

If you run man zip you can read:

-@ file lists.   If  a file list is specified as -@, zip
       takes the list of input files from standard input instead of  from  the
       command line.

You can refer to this question on Unix & Linux Stack Exchange to better understand the difference between standard input and command line argument.

edited Apr 13 '17 at 12:37

Community

1

answered Sep 14 '15 at 14:52

hg8

13,462

3

We used 3 different manuals it seems? funny. – Rinzwind Sep 14 '15 at 14:57
so what exactly does that mean? why would i want to use standard input instead of command line? – clayton33 Sep 14 '15 at 15:03
2

You can find a good explanation on the difference between standard input and command line arguments here. :) – hg8 Sep 14 '15 at 15:07
1

@clayton33 then you can (for example) zip only files a) containing a word (grep -l 'some-word' . -R | zip -@ ....) b) owned by a particular user: find . -type f -user someuser | zip -@ ...) c) zip only duplicate files (fdupes . | zip -@ ...) ... Possibilities are infinite. – muru Sep 14 '15 at 15:23
@Rinzwind that is why you should check http://manpages.ubuntu.com first. – muru Sep 14 '15 at 15:24

score 4 · Answer 2 · answered Sep 14 '15 at 14:52

The manual has this option described as (see man zip from command line or an online version)

 -@     Take the list of input files from standard input.  
        Only  one  filename per line.

So to explain your command. This will have an undetermined amount of results:

 find . -type f -mtime -29 -mtime +21

and the result of this is accepted by the 2nd part of the command but only 1 result at once but still processed to the same zip file.

zip -@ 061110_061201.zip

score 2 · Answer 3 · answered Sep 14 '15 at 14:52

2

according to man zip

-@ file lists.   If  a file list is specified as -@ [Not on MacOS], zip
   takes the list of input files from standard input instead of  from  the
   command line.  For example,

          zip -@ foo

answered Sep 14 '15 at 14:52

Archemar

672

what does the -@ mean when zipping a file in unix?

3 Answers3