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Chilkat2-Python

Read Text at a 32-bit Offset from a Remote SFTP File

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Demonstrates the Chilkat SFtp.ReadFileText32 method, which reads up to a number of bytes from a specific 32-bit byte offset of an open handle and decodes them to text. The arguments are the handle, the offset, the maximum number of bytes, and the charset.

Background: Reading from an explicit offset lets you fetch just the part of a file you need — a header, a record at a known position, a slice of a large log — without downloading everything before it. As with offset writes, the offset counts bytes rather than characters, so it must respect the encoded width of any multibyte content.

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Chilkat2-Python
import sys
import chilkat2

success = False

# Demonstrates the SFtp.ReadFileText32 method, which reads up to a number of bytes from a
# specific 32-bit byte offset of an open handle and decodes them to text.  The 1st argument is
# the handle, the 2nd is the offset, the 3rd is the maximum number of bytes, and the 4th is the
# charset.

sftp = chilkat2.SFtp()

# Connect, authenticate, and initialize the SFTP subsystem.
port = 22
success = sftp.Connect("sftp.example.com",port)
if (success == False):
    print(sftp.LastErrorText)
    sys.exit()

# 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.
password = "mySshPassword"

success = sftp.AuthenticatePw("mySshLogin",password)
if (success == False):
    print(sftp.LastErrorText)
    sys.exit()

success = sftp.InitializeSftp()
if (success == False):
    print(sftp.LastErrorText)
    sys.exit()

handle = sftp.OpenFile("subdir/record.dat","readOnly","openExisting")
if (sftp.LastMethodSuccess == False):
    print(sftp.LastErrorText)
    sys.exit()

# Read 5 bytes starting at byte offset 10, without first reading the bytes before it.
offset = 10
numBytes = 5
text = sftp.ReadFileText32(handle,offset,numBytes,"utf-8")
if (sftp.LastMethodSuccess == False):
    print(sftp.LastErrorText)
    sys.exit()

print(text)

success = sftp.CloseHandle(handle)
if (success == False):
    print(sftp.LastErrorText)
    sys.exit()

sftp.Disconnect()