I can chown a file with chown myuser:mygroup /tmp/file, but how can I see who a file is already chowned to, or who already owns it?  Something like chown --show-who maybe...How can I list the user and group for a file?
Show who a file is chowned to?
chown;privileges
A simple ls -l would do the trick.The -l option to the Unix command ls will list the files using a long format. In short this displays for each file:Unix file typepermissionsnumber of hard linksownergroupsizelast-modified datefilenameExample:$ ls -l-rw-------  1 root  root   9560 23 mar 12:05 .bash_history-rwxr-xr-x  1 root  root    524 28 mai  2007 .bashrcdrwxr-xr-x  3 root  root      3  4 nov 14:51 .cacheFrom the FreeBSD ls man page (Linux one is a bit scarce): The Long Format If the -l option is given, the following information is displayed for each file: file mode, number of links, owner name, group name, MAC label, number of bytes in the file, abbreviated month, day-of-month file was last modified, hour file last modified, minute file last modified, and the pathname. If the modification time of the file is more than 6 months in the past or future, and the -D or -T are not specified, then the year of the last modification is displayed in place of the hour and minute fields. If the owner or group names are not a known user or group name, or the -n option is given, the numeric ID's are displayed. If the file is a character special or block special file, the device num- ber for the file is displayed in the size field.  If the file is a sym- bolic link the pathname of the linked-to file is preceded by ``->''. The listing of a directory's contents is preceded by a labeled total num- ber of blocks used in the file system by the files which are listed as the directory's contents (which may or may not include . and .. and other files which start with a dot, depending on other options). The default block size is 512 bytes.  The block size may be set with option -k or environment variable BLOCKSIZE.  Numbers of blocks in the output will have been rounded up so the numbers of bytes is at least as many as used by the corresponding file system blocks (which might have a different size). The file mode printed under the -l option consists of the entry type and the permissions.  The entry type character describes the type of file, as follows:To know more:wikipedia about lsman ls on FreeBSD (with a nice part about the Long Format)info ls on your GNU/Linux system