Objective-C

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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Objective-C

#import <CkoSFtp.h>
#import <NSString.h>

BOOL success = NO;

//  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.

CkoSFtp *sftp = [[CkoSFtp alloc] init];

//  Connect, authenticate, and initialize the SFTP subsystem.
int port = 22;
success = [sftp Connect: @"sftp.example.com" port: [NSNumber numberWithInt: port]];
if (success == NO) {
    NSLog(@"%@",sftp.LastErrorText);
    return;
}

//  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.
NSString *password = @"mySshPassword";

success = [sftp AuthenticatePw: @"mySshLogin" password: password];
if (success == NO) {
    NSLog(@"%@",sftp.LastErrorText);
    return;
}

success = [sftp InitializeSftp];
if (success == NO) {
    NSLog(@"%@",sftp.LastErrorText);
    return;
}

//  When followLinks is true, a symbolic link is followed and the target's type is returned.
BOOL followLinks = YES;
int result = [[sftp FileExists: @"subdir/report.pdf" followLinks: followLinks] intValue];

//  Interpret the return value.
if (result == -1) {
    NSLog(@"%@",sftp.LastErrorText);
    return;
}

if (result == 0) {
    NSLog(@"%@",@"The path does not exist.");
}

if (result == 1) {
    NSLog(@"%@",@"A regular file exists.");
}

if (result == 2) {
    NSLog(@"%@",@"A directory exists.");
}

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

[sftp Disconnect];