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# LogiView

## Function 'exists'

| This function verifies existence and access rights of the specified file.
| Syntax:
| {LOG_VAR}= exists({STR_EXPR},{"r"|"w"|"x"}) or {LOG_VAR}= exists({STR_EXPR},{"r"|"w"|"x"},{"/CLIENT"})
| ### I/O parameters:
| {STR_EXPR} | Name of file (including path).
| {"r"|"w"|"x"} | Check access rights:
"r" | read access
"w" | write access
"x" | execution
| "/CLIENT" | Check on client side
| - |
| ### Return value:
| {LOG_VAR} |
TRUE | File and access rights verified
FALSE | File not found.
| ### Example:
| Declaration of Variables
     10 C -- Pre-definiton of variables
     20   DOCU_INT_2 = 0
     30   DOCU_STRING_1 = "/tmp/test.seite"
     40 C -- If file is found on client computer and can be opened for
             read access,
     50 if (exists(DOCU_STRING_1,"w", "/CLIENT")==TRUE)
     60 C -- Open file for write access
     70    DOCU_INT_1 = open(DOCU_STRING_1,"w")
     80 C  -- modify and close file
     90    .........
    100 close(DOCU_INT_1)
    110 else
    120 C  -- file not found or write access not allowed
    130    put("This file cannot be accessed on the client computer!")
    140 endif
| Result:
| If the file is not found on the client computer or if write access is not allowed, an error message ("This file cannot be accessed on the client computer!") is displayed. Otherwise, the file is processed.
| Functions and commands: File Interface