|Home||Switchboard||Unix Administration||Red Hat||TCP/IP Networks||Neoliberalism||Toxic Managers|
May the source be with you, but remember the KISS principle ;-)
Skepticism and critical thinking is not panacea, but can help to understand the world better
|News||SSH||Recommended Links||WinSCP||LFTP -- an excellent ftp/sftp client||Chrooting SFTP||chrooting sshd/sftp on Solaris|
|Private and Public key management||ssh-keygen||SCP||WinSCP Tips||Securing SSH daemon||sshfs|
|SSH Usage in Pipes||Passwordless SSH login||Port Forwarding||SSH History||Tips||Humor||Etc|
SFTP is normally used as an interactive application/protocol, but also can be put into a batch mode with the -b flag. This can be specified with a file or can be directed stdin from an external script.
The password can not be passed by either process.
sftp [-1Cv] [-b batchfile] [-F SSH_config] [-o SSH_option] [-s subsystem | sftp_server] [-S program] host
sftp [[user@]host[:file [file]]]
But mostly SFTP is used as an interactive file transfer program.
With FTP one might try to copy up all their JPG files to their image directory like this:
ftp> cd /home/user/images/
ftp> mput *.jpg
With SFTP it is much simpler..
sftp> cd /home/user/images/
sftp> put *.jpgtt>
List of SFTP commands (SFTP will abort if any of the following commands fail):
List of other commands:
SFTP may also use many features of SSH, such as public key authentication and compression. SFTP connects and logs into the specified host, then enters an interactive command mode. The second usage format will retrieve files automatically if a noninteractive authentication method is used; otherwise it will do so after successful interactive authentication. The last usage format allows the sftp client to start in a remote directory.
Here are the options used:
Part of the OpenSSH (Open Source Secure Shell) project, Secure FTP (sftp) is another file-transfer program that works in a similar way to FTP but encrypts the transfer so that it cannot be intercepted or read by intermediary computers. The encryption process increases the amount of data and slows the transfer but provides protection for confidential information.
You must specify the computer and user account on the sftp command line. SFTP prompts you for the password.$ sftp root@our_web_site.com:/etc/httpd/httpd.conf Connecting to our_web_site.com... root@our_web_site.coms password: Fetching /etc/httpd/httpd.conf to httpd.conf
For security purposes, SFTP normally asks the user for the Linux login password. It doesn't request the password from standard input but from the controlling terminal. This means you can't include the password in the batch file. The solution to this problem is to use SSH's public key authentication using the ssh-keygen command. If you have not already done so, generate a new key pair as follows.$ ssh-keygen -t rsa
A pair of authentication keys are stored under .ssh in your home directory. You must copy the public key (a file ending in .pub) to the remote machine and add it to a text file called ~/.sshd/authorized_keys. Each local login accessing the remote login needs a public key in authorized_keys. If a key pair exists, SFTP automatically uses the keys instead of the Linux login password.
Like FTP, SFTP needs a list of commands to carry out. SFTP includes a -b (batch) switch to specify a separate batch file containing the commands to execute. To use a convenient here file in your script, use a batch file called /dev/stdin.
The commands that SFTP understands are similar to FTP. For purposes of shell scripting, the basic transfer commands are the same. Transfers are always "binary." There is a -v (verbose) switch, but it produces a lot of information. When the -b switch is used, SFTP shows the commands that are executed so the -v switch is not necessary for logging what happened during the transfer.sftp -C -b /dev/stdin root@our_web_site.com <<! cd /etc/httpd get httpd.conf ! STATUS=$? if [ $STATUS -ne 0 ] ; then printf "%s\n" "Error: SFTP transfer failed" >&2 exit $STATUS fi
The -C (compress) option attempts to compress the data for faster transfers.
For more information about ssh, sftp, and related programs, visit http://www.openssh.org/.
Even though the Linux version of the sftp client doesn't offer a direct way to resume an interrupted transfer, doing so is quite simple by using common shell tools, as long as you are able to login to the remote server through a console. Assuming that you are transferring data.zip from source_server to target_server and the transfer was interrupted, you can do the following:
- Connect to target_server using ssh, since you will be required to perform some operations there. Navigate to the directory containing the partially transferred file (also called data.zip)
- Check the sizes of the original and the partially transferred files. The easiest way to do that is by using the ls -al data.zip command. Let's assume that data.txt is 8231129 bytes long, and only 2811110 bytes were transferred before the interruption
- Subtract the size of the partially transferred file from the original, to get the remaining size in bytes. In this case, it is 5420019 bytes. In case you didn't know, Linux has a practical command-line calculator, bc, which comes very handy for quick calculations
- In source_server, create a new file consisting of the last 5420019 bytes of the original. You can do this with the tail command: tail -c 5420019 data.zip >data.tail
- Transfer the data.tail file to target_server, using sftp as usually.
- Once the transfer is complete, delete data.tail from source_server to avoid any mistake that would corrupt your original file.
- In target_server, use the cat command to append data.tail to the partially transferred file: cat data.tail >>data.zip (Note the double >>)
This works for both text and binary files. Apparently a better way would be integrating this ability into the sftp client, which is the way some clients such as putty and winscp work, but until that happy day you can use the tips above as a workaround.
lftp is a very nice command line ftp client, which supports tab completion, directory mirroring and of course resuming of interrupted downloads. It can also work as an sftp client, with the right protocol prefix, e.g. lftp sftp://user@host, and can even be used in batch mode. You can find a copy at http://lftp.yar.ru/. Still, nice trick :)
Google matched content
Groupthink : Two Party System as Polyarchy : Corruption of Regulators : Bureaucracies : Understanding Micromanagers and Control Freaks : Toxic Managers : Harvard Mafia : Diplomatic Communication : Surviving a Bad Performance Review : Insufficient Retirement Funds as Immanent Problem of Neoliberal Regime : PseudoScience : Who Rules America : Neoliberalism : The Iron Law of Oligarchy : Libertarian Philosophy
War and Peace : Skeptical Finance : John Kenneth Galbraith :Talleyrand : Oscar Wilde : Otto Von Bismarck : Keynes : George Carlin : Skeptics : Propaganda : SE quotes : Language Design and Programming Quotes : Random IT-related quotes : Somerset Maugham : Marcus Aurelius : Kurt Vonnegut : Eric Hoffer : Winston Churchill : Napoleon Bonaparte : Ambrose Bierce : Bernard Shaw : Mark Twain Quotes
Vol 25, No.12 (December, 2013) Rational Fools vs. Efficient Crooks The efficient markets hypothesis : Political Skeptic Bulletin, 2013 : Unemployment Bulletin, 2010 : Vol 23, No.10 (October, 2011) An observation about corporate security departments : Slightly Skeptical Euromaydan Chronicles, June 2014 : Greenspan legacy bulletin, 2008 : Vol 25, No.10 (October, 2013) Cryptolocker Trojan (Win32/Crilock.A) : Vol 25, No.08 (August, 2013) Cloud providers as intelligence collection hubs : Financial Humor Bulletin, 2010 : Inequality Bulletin, 2009 : Financial Humor Bulletin, 2008 : Copyleft Problems Bulletin, 2004 : Financial Humor Bulletin, 2011 : Energy Bulletin, 2010 : Malware Protection Bulletin, 2010 : Vol 26, No.1 (January, 2013) Object-Oriented Cult : Political Skeptic Bulletin, 2011 : Vol 23, No.11 (November, 2011) Softpanorama classification of sysadmin horror stories : Vol 25, No.05 (May, 2013) Corporate bullshit as a communication method : Vol 25, No.06 (June, 2013) A Note on the Relationship of Brooks Law and Conway Law
Fifty glorious years (1950-2000): the triumph of the US computer engineering : Donald Knuth : TAoCP and its Influence of Computer Science : Richard Stallman : Linus Torvalds : Larry Wall : John K. Ousterhout : CTSS : Multix OS Unix History : Unix shell history : VI editor : History of pipes concept : Solaris : MS DOS : Programming Languages History : PL/1 : Simula 67 : C : History of GCC development : Scripting Languages : Perl history : OS History : Mail : DNS : SSH : CPU Instruction Sets : SPARC systems 1987-2006 : Norton Commander : Norton Utilities : Norton Ghost : Frontpage history : Malware Defense History : GNU Screen : OSS early history
The Peter Principle : Parkinson Law : 1984 : The Mythical Man-Month : How to Solve It by George Polya : The Art of Computer Programming : The Elements of Programming Style : The Unix Haterís Handbook : The Jargon file : The True Believer : Programming Pearls : The Good Soldier Svejk : The Power Elite
Most popular humor pages:
Manifest of the Softpanorama IT Slacker Society : Ten Commandments of the IT Slackers Society : Computer Humor Collection : BSD Logo Story : The Cuckoo's Egg : IT Slang : C++ Humor : ARE YOU A BBS ADDICT? : The Perl Purity Test : Object oriented programmers of all nations : Financial Humor : Financial Humor Bulletin, 2008 : Financial Humor Bulletin, 2010 : The Most Comprehensive Collection of Editor-related Humor : Programming Language Humor : Goldman Sachs related humor : Greenspan humor : C Humor : Scripting Humor : Real Programmers Humor : Web Humor : GPL-related Humor : OFM Humor : Politically Incorrect Humor : IDS Humor : "Linux Sucks" Humor : Russian Musical Humor : Best Russian Programmer Humor : Microsoft plans to buy Catholic Church : Richard Stallman Related Humor : Admin Humor : Perl-related Humor : Linus Torvalds Related humor : PseudoScience Related Humor : Networking Humor : Shell Humor : Financial Humor Bulletin, 2011 : Financial Humor Bulletin, 2012 : Financial Humor Bulletin, 2013 : Java Humor : Software Engineering Humor : Sun Solaris Related Humor : Education Humor : IBM Humor : Assembler-related Humor : VIM Humor : Computer Viruses Humor : Bright tomorrow is rescheduled to a day after tomorrow : Classic Computer Humor
The Last but not Least Technology is dominated by two types of people: those who understand what they do not manage and those who manage what they do not understand ~Archibald Putt. Ph.D
Copyright © 1996-2020 by Softpanorama Society. www.softpanorama.org was initially created as a service to the (now defunct) UN Sustainable Development Networking Programme (SDNP) without any remuneration. This document is an industrial compilation designed and created exclusively for educational use and is distributed under the Softpanorama Content License. Original materials copyright belong to respective owners. Quotes are made for educational purposes only in compliance with the fair use doctrine.
FAIR USE NOTICE This site contains copyrighted material the use of which has not always been specifically authorized by the copyright owner. We are making such material available to advance understanding of computer science, IT technology, economic, scientific, and social issues. We believe this constitutes a 'fair use' of any such copyrighted material as provided by section 107 of the US Copyright Law according to which such material can be distributed without profit exclusively for research and educational purposes.
This is a Spartan WHYFF (We Help You For Free) site written by people for whom English is not a native language. Grammar and spelling errors should be expected. The site contain some broken links as it develops like a living tree...
|You can use PayPal to to buy a cup of coffee for authors of this site|
Last modified: March 12, 2019