Ubuntu – find: missing argument to -exec

bashfindjava

The following works from the terminal no problem

find testDir -type f -exec md5sum {} \;

Where testDir is a directory that contains some files (for example file1, file2 and file3).

However, if I run this from a bash script or from Java using something like

Runtime rt = Runtime.getRuntime();
Process pr = rt.exec("find testDir -type f -exec md5sum {} \\;");

I get the following error

find: missing argument to `-exec'

Any ideas?

UPDATE: This was answered correctly over on stackoverflow. I will close the question here. https://stackoverflow.com/questions/10704889/java-execute-command-line-program-find-returns-error

Best Answer

The \ in -exec md6sum {} \; is necessary to prevent the shell from interpreting the ; character as command separator. If Java does not execute the command in a shell, try removing the escaping \\ so that the code becomes:

Runtime rt = Runtime.getRuntime();
Process pr = rt.exec("find testDir -type f -exec md5sum {} ;");

I have just confirmed this behavior with the next test program:

import java.io.*;
class Xx {
    public static void main(String args[]) throws Exception {
        Process p = Runtime.getRuntime().exec("/bin/echo \\;");
        InputStream in = p.getInputStream();
        int c;
        while ((c=in.read()) != -1)
            System.out.write((char)c);
        p.waitFor();
    }
}

Compiled with javac Xx.java, java Xx outputs \;. If I remove the \\, it'll print ; as expected.

Related Solutions

Ubuntu – “find: missing argument to `-exec’” when using “-exec rm -f {}\”

You missed the a ; at the end (and a space too between {} and ;). The correct command is:

find . -type f -name "IMAG1806.jpg" -exec rm -f {} \;

; indicates the end of -exec predicate of find.

Also note that we have used \; i.e. \ in front of ; to escape the interpretation of ; by shell, otherwise shell will treat ; as end of the whole find command and find will throw the same error. You can also use ';' instead of \;.

You were using \ at the end, this indicates your shell will continue to take input via PS2 (indicated by >), you typed IMAG1806.jpg again, so the whole command becomes:

find . -type f -name "IMAG1806.jpg" -exec rm -f {}IMAG1806.jpg

As you can see this is not a valid command at all with IMAG1806.jpg at the end, no closing of -exec predicate and without a space between {} and \;.

Ubuntu – What’s the missing argument to -exec

The user in that post may said that the + sign at the end of a -exec command is faster, but not why.

Lets assume the find command return the following files:

/path/to/file1
/path/to/file2
/path/to/file3

The normal -exec command (-exec command {} \;) runs once for each matching file. For example:

find ... -exec mv {} /target/ \;

Executes:

mv /path/to/file1 /target/
mv /path/to/file2 /target/
mv /path/to/file3 /target/

If you use the + sign (-exec command {} +) the command is build by adding multiple matched files at the end of the command. For example:

find ... -exec mv -t /target/ {} +

Executes:

mv -t /target/ /path/to/file1 /path/to/file2 /path/to/file3

To use the + flag correctly the argument to process must be at the end of the command, not in the middle. That's why find trows missing argument to '-exec' in your example; it misses the closing {}.

Best Answer

Related Solutions

Ubuntu – “find: missing argument to `-exec’” when using “-exec rm -f {}\”

Ubuntu – What’s the missing argument to -exec

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