Xbase++

Check if a Remote File or Directory Exists

Demonstrates the Chilkat SFtp.FileExists method, which checks a remote path and returns an integer describing what is there. The first argument is the remote path and the second (followLinks) selects whether a symbolic link is followed to its target. The return value is -1 on error, 0 if nothing exists, 1 for a file, 2 for a directory, 3 for a symbolic link, and higher values for special entry types.

Background: This returns more than a yes/no because "does it exist" usually comes with "and is it the kind of thing I expect" — a job that means to write a file should notice if a directory already occupies the path. The followLinks flag decides whether a symbolic link is reported as a link (3, only when not following) or transparently resolved to its target's type. Always handle the -1 case: it means the check itself failed, which is different from the path not existing.

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LOCAL nSuccess
LOCAL oSftp
LOCAL nPort
LOCAL cPassword
LOCAL nFollowLinks
LOCAL nResult

nSuccess := 0

//  Demonstrates the SFtp.FileExists method, which checks a remote path and returns an integer
//  describing what is there.  The 1st argument is the remote path and the 2nd (followLinks)
//  selects whether a symbolic link is followed to its target.

oSftp := CreateObject("Chilkat.SFtp")

//  Connect, authenticate, and initialize the SFTP subsystem.
nPort := 22
nSuccess := oSftp:Connect("sftp.example.com", nPort)
IF (nSuccess == 0)
    ? oSftp:LastErrorText
    oSftp:destroy()
    RETURN
ENDIF

//  Normally you would not hard-code the password in source.  You should instead obtain it
//  from an interactive prompt, environment variable, or a secrets vault.
cPassword := "mySshPassword"

nSuccess := oSftp:AuthenticatePw("mySshLogin", cPassword)
IF (nSuccess == 0)
    ? oSftp:LastErrorText
    oSftp:destroy()
    RETURN
ENDIF

nSuccess := oSftp:InitializeSftp()
IF (nSuccess == 0)
    ? oSftp:LastErrorText
    oSftp:destroy()
    RETURN
ENDIF

//  When followLinks is 1, a symbolic link is followed and the target's type is returned.
nFollowLinks := 1
nResult := oSftp:FileExists("subdir/report.pdf", nFollowLinks)

//  Interpret the return value.
IF (nResult == -1)
    ? oSftp:LastErrorText
    oSftp:destroy()
    RETURN
ENDIF

IF (nResult == 0)
    ? "The path does not exist."
ENDIF

IF (nResult == 1)
    ? "A regular file exists."
ENDIF

IF (nResult == 2)
    ? "A directory exists."
ENDIF

//  Other possible values: 3 = symbolic link (only when followLinks is 0), 4 = special
//  entry, 5 = unknown, 6 = socket, 7 = character device, 8 = block device, 9 = FIFO.

oSftp:Disconnect()

oSftp:destroy()