Hi,

I want to copy everything in one folder "log" to an existed folder "logbackup" without asking me overwrite or not. Just overwrite it.

both "cp -a" and "cp -rf" need me to confirm overwrite or not.

Thanks in advance!

sscn

-f WILL force an overwrite, it will never ask to confirm.

try this

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Check for aliases, you may have noclobber or interactive included transparently

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sscn,

check what is the output of the command alias. I think there might be an alias for cp like alias cp='cp -i', which is why cp -rf asking for confirmation.

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unalias -a is useful in scripts

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After I use "unalias -a", cp -rf doesn't need to confirm overwrite.

My alias output.

alias cp='cp -i'
alias l.='ls -d .* --color=auto'
alias ll='ls -l --color=auto'
alias ls='ls --color=auto'
alias mv='mv -i'
alias rm='rm -i'
alias which='alias | /usr/bin/which --tty-only --read-alias --show-dot --show-tilde'

try the command which I gave

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Hi deep27ak,

I am trying rsync. To me, rsync is a big tool to be used in my case.

1) rsync efficiency is not better than cp command for new added stuff;
2) If logbackup folder has very big data like 40GB, the increament list created by rsync takes too much time.

I just need to copy new created logs to the backup folder.

Pls correct me if I am wrong on rsync.

Thanks a lot.

sscn,

It's the other way round, rsync is better than cp, as rsync compares the checksum of the files and it's used even when syncing files across systems.

I suspect the alias cp is in your .bashrc or .bash_profile files, you can just uncomment that or remove so that cp -rf works without confirmation.

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Another trick is to simply respond yes.
cp -rf source/* /destination/ < <(yes y)

I'll sometimes use "< <(yes n)" to prevent overwriting files.

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aliasing works!

rsync is much better for backing up than cp, by far. Yes the increment list takes a long time on a big archive, but the advantage is rsync will ONLY copy over those files which have changed, whereas cp will overwrite everything, every time. If your disc has an 80MB/s write speed and you're backing up a 40GB archive, cp will take a minimum of 8-9 minutes. If it's a lot of small files, it could easily take upwards of 30 minutes or more. On the same operation, rsync may take 2-3 minutes to build up the increment list, but then it might only take 20 seconds to copy the changed files over, depending on how many have changed since the last backup. It's especially useful when backing up across a network connection, or the internet.

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It is even better than that. rsync detects the changes and copies only what actually has changed. If you have for example a large log-file and only a few lines have changed rsync will not copy the whole file, but only the changes.

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