This function reports whether or not file and directories exist.
Y is a character vector or scalar containing a single file/directory name, or a vector of character vectors containing zero or more file/directory names.
If Y specifies a single name, the result R is a scalar 1 if a file or directory exists or 0 if not. If Y is a vector of character vectors, R is a vector of 1s and 0s with the same length as Y.
⎕NEXISTS may be applied using the Variant operator with the Wildcard option.
| 0 | The name or names in Y identifies a specific file name. | 
| 1 | The name or names in Y that specify the base name and extension (see File Name Parts), may also contain the wildcard characters "?" and "*". An asterisk is a substitute for any 0 or more characters in a file name or extension; a question-mark is a substitute for any single character. | 
If the Wildcard option is 1, R indicates whether or not one or more matches to the corresponding pattern in Y exist.
      ⎕←⎕MKDIR'/Users/Pete/Documents/temp/t1/t2'
1
      ⎕NEXISTS'/Users/Pete/Documents/temp/t1/t2'
1
      ⎕NEXISTS'/Users/Pete/Documents/temp/t1/t2/pd'
0
      ⊢⎕MKDIR'temp1' 'temp2'
1 1
      ⎕NEXISTS 'temp1' 'temp2' 'temp3'
1 1 0
      (⎕NEXISTS⍠1) 't*'
1
        If Y is a symbolic link, ⎕NEXISTS will return 1 whether or not the target of the symbolic link exists.