How to Transfer Files with LFTP and Create Directories in Bash?

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Transferring files between servers using Bash can often be streamlined with tools like LFTP. When you're working with multiple servers, it's essential to ensure that the directory exists before attempting to upload files. In this article, we'll demonstrate how to transfer files from server A to server B, check for the existence of directories, and efficiently use LFTP commands.

Understanding Directory Checks during LFTP Transfer


When you're using LFTP for file transfers, it's critical to manage directories effectively. If a specific directory does not exist on the remote server, trying to upload files can result in errors. Therefore, it is advisable to check for the existence of a directory before running your upload commands.

Creating a Directory Only if It Doesn't Exist


LFTP offers a straightforward way to check for existing directories with a combination of commands. Instead of running a command that fails if the directory already exists, you can execute a conditional check. Here’s how to do this within your LFTP session.

LFTP Session Code Example


Here’s a complete sample code snippet to transfer files from server A (test-lx) to server B (test2-lx) while creating a target directory only if it does not exist:

lftp -u drop-up,1Q2w3e4R ftp://ta1bbn01:21 << EOF

# Navigate to the desired folder
cd $desFolder

# Check if the directory exists and create it if it doesn't
if ! ls | grep -q '^test$'; then
mkdir test
fi

# Change to the test directory
cd test

# Transfer multiple files in one command
put $srcFil
put $srcFile

bye
EOF

Breakdown of the Code:

1. 
   Connecting to LFTP: The command begins with the lftp command to establish a connection to the FTP server using specified user credentials.
   
   
2. 
   Navigating to the Target Directory: Using cd $desFolder, we navigate to the directory where we want to manage our files.
   
   
3. 
   Directory Check: The command if ! ls | grep -q '^test$'; then mkdir test; fi checks if the directory named test exists. If it doesn't, it creates the directory. This can prevent errors when you attempt to cd into a non-existent directory.
   
   
4. 
   Remaining Operations: After ensuring the directory's existence, change into the test folder using cd test, then upload the desired files using put $srcFil and put $srcFile. You can chain multiple put commands this way to manage file transfers effectively.
   

Using find Command for Directory Existence Check


You also inquired about using the find command to check for directory existence. The command you've mentioned find -maxdepth 1 -name DirName is typically used in Unix-like systems to search for files or directories. However, when working within an LFTP session, such checks don’t translate directly, as LFTP operates in a different context. Therefore, managing directory checks as shown in the above example is more suitable.

Conclusion


With the right commands, managing file transfers and directory existence can be accomplished in one seamless operation using LFTP. By checking if a directory exists before creating it and efficiently grouping file transfers, you optimize the process, making your Bash scripting less error-prone.

Frequently Asked Questions (FAQ)

Can I run other commands during an LFTP session?


, LFTP supports multiple commands, allowing you to script a variety of operations to suit your needs.

Is there a limit to how many files I can transfer in one command?


No, you can transfer as many files as needed by stacking put commands in your script effectively.

What if I need to transfer different file types?


You can specify different file types with wildcards; for instance, use mput *.txt to upload all .txt files at once.

By following these guidelines, transferring files between servers with LFTP becomes a hassle-free task.

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