Most of the commands discussed in this topic accept options. Shell command options are usually specified by a minus sign (–) followed by a single character. For example, the ls command simply lists a directory's contents in multiple columns on your screen. However:

ls –F

distinguishes between various file types when listing the contents of a directory. (See Listing directory contents for an example.)

ls –1

lists directory names in a single column.

Options consisting of a minus sign followed by a character are called simple options. You specify simple options after the name of the command and before any other arguments for the command (that is, arguments that are not options). For example, you would enter:

ls –1 dir1

to list the contents of dir1 in a single column.

The order of options and arguments is important. If you enter:

ls dir1 –F

ls lists the contents of dir1 and then tries to list the contents of the directory, or attributes of the file, called –F.

As a special notation, most tcsh shell commands let you specify a double minus sign (--) to separate the options from the nonoption arguments; -- means that there are no more options. Thus, if you really have a directory named –F, you could enter:

ls -- –F

to list the contents of that directory or the file attributes.

The tcsh shell gives you a shorthand way to specify more than one simple option to a command. For example, –t and –v are both simple options that you can specify with the cat command. (To find out what these options do, read the cat command description in z/OS UNIX System Services Command Reference.) You could enter:

cat –t –v file

or you could combine the two options into:

cat –tv file

The order of the options is not important:

cat –vt file

is equivalent to the previous version of the command.