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Accepted
Eonil
Asked: 2010-06-23 18:55:30 +0800 CST

How to let 'cp' command don't fire an error when source file does not exist?

  • 772

I'm using Mac OS X. I'm trying to copying some files with cp command for a build script like this.

cp ./src/*/*.h ./aaa

But this command fires an error if there is no .h file in ./src directory. How to make the command don't fire the error? (silent failure) The error makes build result fail, but I just want to copy when only there are some header file.

shell copy

6 Answers

  1. Best Answer

    If you're talking about the error message, you can suppress that by sending it to the bit bucket:

    cp ./src/*/*.h ./aaa 2>/dev/null

    If you want to suppress the exit code and the error message:

    cp ./src/*/*.h ./aaa 2>/dev/null || :
    • 122

  2. You're looking for something along the lines of

    if [ -e file ]
 then cp file /somewhere
fi

    (Unfortunately, the -f option is not the droid you're looking for.)

    If you want to match a glob, that won't work; use find instead, e.g.:

    find ./src -name \*.h -exec cp {} ./destination \;
    • 20

  3. Old question, but might still be relevant for others.
    If you don't need to use cp, you could try with rsync.
    To copy all files from a source to a destination directory, run:

    rsync -avzh --ignore-errors /path/to/source /path/to/destination

    Rsync comes with most Unix-like systems such as Linux, Mac OS X or FreeBSD.

    • 13

  4. Piping the result to true ensures that the command will always succeed. I have tried this on Linux but not on any Mac OS:

    cp ./src/*/*.h ./aaa | true
    • 12

  5. You could force the correct error status. With a function:

    $ cpalways () { cp $1 $2 2>/dev/null ; return 0 ; }

    Given the following:

    $ ls foo bar baz
ls: baz: No such file or directory
bar foo

    Regular copy will return an error. It will return an exit status of 1. 

    $ cp baz bar ; echo $?
cp: baz: No such file or directory
1

    If we use the cpalways() function above, any errors will be hidden:

    $ cpalways baz bar ; echo $?
0
$ cpalways foo bar ; echo $?
0
$ cpalways baz bar ; echo $?
0
    • 2

  6. This works

    $(cp ./src/*/*.h ./aaa | true)

    • -1