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Copying a Directory on a UNIX System

Posted on 2013-12-17
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Last Modified: 2013-12-31
I've always preferred using the tar command instead of the cp command to copy the content of a directory on a UNIX system. That's because I found that using the cp command was unpredictable and unreliable. I know there are those who are fond of cpio. Anyway, I was just wondering whether my misgivings about the cp command are justified.
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Question by:babyb00mer
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by:xterm
ID: 39724519
I only encounter one real issue when using cp vs. tar, and that is that if your source directory has the same name as the destination, it will end up inside the destination directory.

So for jobs that I do repetitively, I prefer:

(cd /source/directory && tar cpf - dir1 dir2 dirX ) | (cd /dest/directory && tar xvfp -)

over:

cp -Rv /source/directory /dest/directory

But to answer your question, misgivings are much the same as preferences which means you don't have to "justify" them per se - you should use what gets the job done and poses the least stress or risk to you.
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by:babyb00mer
ID: 39732588
Hmm. I'm wondering whether tar is faster than cp.
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by:xterm
ID: 39732592
No, tar isn't any faster - from a system standpoint, they're doing virtually the identical thing.
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by:phoffric
ID: 39732624
>> unpredictable and unreliable
How is it unpredictable?
How is it unreliable?
Curious - are you using NFS?

For performance considerations, if the cp is over a network and if you have 1000's of files being copied, then transmitting a tar archive, a single file, incurs less overhead than transmitting many files.
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Anacreo earned 250 total points
ID: 39744605
cpio is more reliable than tar in my opinion, file name lengths and directory loops can become issues, hard links as well.

find . | cpio -pdum /var/tmp/target

tar and cpio are old and have numerous limitations that can bite you... a more modern solution is to use pax:
    mkdir /tmp/to
    cd /tmp/from
    pax -rw . /tmp/to


But on any system that has rsync, why not go with the gold standard.
rsync -az -H --delete /path/to/source /path/to/dest
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