Add command line instructions

external/exchange-channels/lft/lft.md

@@ -66,11 +66,25 @@ Encrypted files are by default kept on your disc after decryption. If you want t
 
 ## Accessing LFT via Command-Line Tool
 
-To access LFT via command line you need to have Aspera CLI (Command Line Interface) be installed. It should be preinstalled during installation of **IBM Aspera Connect** client (see step 2 above). Or you can download it manually on the [IBM website](https://www.ibm.com/products/aspera/downloads?list) and click on the "download now" under the Section "IBM Aspera CLI".
+1. To access LFT via command line you need to have Aspera CLI (Command Line Interface) be installed. It should be preinstalled during installation of **IBM Aspera Connect** client (see step 2 above). Or you can download it manually on the [IBM website](https://www.ibm.com/products/aspera/downloads?list) and click on the "download now" under the Section "IBM Aspera CLI".
 
-Go to the help section of your access link
+2. To transfer data you need to authenticate your connection. Authentication is done via SSH for which you need **SSH private key**. That key comes with the Aspera Connect installation and is named `asperaweb_id_dsa.openssh` (see Note below). You need to know the location of SSH private key. Please see the table below for the list of locations depanding on your operational system:
+
+| Environment | Location | Alternate location |
+| MacOS	| $HOME/Applications/Aspera\ Connect.app/Contents/Resources/asperaweb_id_dsa.openssh | /Applications/Aspera\ Connect.app/Contents/Resources/asperaweb_id_dsa.openssh |
+| Windows | C:\\Program Files (x86)\Aspera\Aspera Connect\etc\asperaweb_id_dsa.openssh |C:\\Users\username\AppData\Local\Programs\Aspera\Aspera Connect\etc\asperaweb_id_dsa.openssh |
+| Linux | $HOME/.aspera/connect/etc/asperaweb_id_dsa.openssh | /opt/aspera/etc/asperaweb_id_dsa.openssh |
+| Iris | /opt/apps/resif/data/production/$PROD_VERSION/default/software/tools/Aspera-CLI/$CLI_VERSION/etc/asperaweb_id_dsa.openssh | |
+
+3. Go to the help section of your access link into Download or Upload tab.
+
+<br/> ![Alt](img/lft_help.png "Help section") <br/><br/>
+<br/> ![Alt](img/lft_helpCommandLine.png "Help tabs") <br/><br/><br/>
+
+Export variables as stated in Download/Upload tab of help section and execute the command for download/upload data.
+
+<br/> ![Alt](img/lft_command.png "Help command") <br/><br/><br/>
 
-<br/> ![Alt](img/lft_help.png "Help section") <br/><br/><br/>
 
 And follow the steps in the **Using the command line** section.
 
@@ -96,3 +110,12 @@ Specifically your firewall should:
 * If you have a local firewall on your server (like Windows Firewall), verify that it is not blocking your SSH and fasp transfer ports (e.g. TCP/UDP 33001).
 
 Detailed information on how to configure firewalls when working with Aspera is given [here](https://download.asperasoft.com/download/docs/p2p/3.5.1/p2p_admin_win/webhelp/dita/configuring_the_firewall.html).
+
+### Command-Line error "command not found: ascp" ###
+
+Run <code>ascli config ascp show</code> to show path of <code>ascp</code>.
+
+Modify command with the path instead of <code>ascp</code>:<br>
+Here is an example of download command
+
+`<path-to-ascp-executable> -d -i $SSHKEY -P 33001 --file-crypt decrypt -W $TOKEN app_duma_private@aspera.lcsb.uni.lu:/<remote-dir> </local-dir>`
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