Doug Stamford wrote: > One of my co-workers brought to my attention a most unusual problem with > the cp command. Originally, this problem was discovered on a AIX system > but he also found this problem exist on the Linux system. He contacted > IBM directly to inform them, but was told the cp command was functioning > properly.
They were correct. The cp command is functioning properly from your description of the behavior. But perhaps they didn't explain why well enough? I will give it a try. > The problem on occurs when using the cp command and there are only 2 > source files and the '*' is used, and the destination is inadvertently > left off. The shell expands file glob characters. The '*' is a file glob (because it matches a glob of characters) and the cp command never sees the '*'. The cp command sees the expansion. It is not possible for the cp command to know that you entered a '*' and not two file names. The cp command does not receive a '*' argument. The cp command recieves actual file arguments, in this case as expanded by the command shell. The command shell expands all file globs to match files and convert them into actual file names. > mkdir test > cat /etc/snmp/snmpd.conf > test/file1.txt > cat /usr/local/apache/conf/httpd.conf > test/file2.txt > cp test/*.txt <enter> > > You will now notice no error output and the file2.txt is the same as > file1.txt Because there were only two files in the directory the '*' was expanded by the shell to match two file names. The cp command was given two filename arguments. You can use the 'echo' command to show you what is being done. echo cp test/*.txt The output of the echo will show you that the command you are invoking is: cp test/file1.txt test/file2.txt With that command cp is then copying from one file to the other as it has been instructed to do. If there are three program arguments then the last one must be a directory or it is an error. But with only two it isn't possible to determine the caller's intention. Hope that helps, Bob _______________________________________________ Bug-coreutils mailing list Bug-coreutils@gnu.org http://lists.gnu.org/mailman/listinfo/bug-coreutils
