Using the System

01

HPC Cluster Access

Overview

PARAM Shakti is a high-performance computing (HPC) cluster managed by the Computer and Informatics Centre (CIC), IIT Kharagpur. Access to the cluster is granted exclusively through secure shell (SSH) to the designated login node, which serves as the gateway to the compute resources. All computational work must be submitted via the Slurm job scheduler — direct execution of resource-intensive tasks on the login node is strictly prohibited.

The login node is intended only for:

Job Submission and Monitoring
File / Data Transfer
Lightweight Compilation (for large builds, submit as a Slurm job)

Two primary storage areas are available to all users:

/home — Persistent user home directory (backed up; limited quota)
/scratch — High-performance temporary storage (not backed up; use for job input/output)

Two-Factor Authentication (2FA) Setup

PARAM Shakti enforces two-factor authentication (2FA) for enhanced security. Follow these steps to set up and use 2FA.

Step 1: Install Google Authenticator

Download the Google Authenticator app on your smartphone:

Android: Google Play Store
iOS: App Store

Step 2: First-Time Login & 2FA Enrolment

Connect to the Cluster via SSH (see connection instructions below).
Complete the CAPTCHA challenge.
Enter your temporary system-generated password (from your welcome email). The system automatically triggers 2FA enrolment on first login:

====================================
 Google Authenticator Setup Required
====================================

Generating new secret...
Warning: pasting the following URL into your browser exposes the OTP secret to Google:
  https://www.google.com/chart?chs=200x200&cht=qr&chl=otpauth://totp/username@login06

Your new secret key is: MG3SKYXXATJ6HDU7DNNT7NLQZY
Your verification code is: 484110
Your emergency scratch codes are:
  28922917
  51703442
  55918526
  96525150
  37413055

IMPORTANT: Scan the QR code with Google Authenticator app.
From next login, OTP will be mandatory.

Set a new password when prompted (must comply with Password Policy below).
Scan the QR code shown in your terminal using Google Authenticator.
Open Google Authenticator → tap "+" → "Scan a QR code".
A new entry (e.g., login06: username@login06) will appear in your app:
Enter the 6-digit OTP (refreshes every 30 s) when prompted to complete setup.

Save your emergency backup codes! During setup, you'll receive 4–5 one-time-use emergency codes. Store them securely offline (e.g., printed or in a password manager). These are critical if you lose phone access.

[username@login06 ~]$ google-authenticator
Do you want authentication tokens to be time-based (y/n): y
Warning: pasting the following URL into your browser exposes the OTP secret to Google:
  https://www.google.com/chart?chs=200x200&cht=qr&chl=otpauth://totp/username@login06

Your new secret key is: XYAIF2N03MC2OTFHCPQNLIT7YE5
Your verification code is: 171011
Your emergency scratch codes are:
  53645187
  39749829
  53082287
  93384487
  70637813

Do you want me to update your '/home/username/.google_authenticator' file? (y/n): y

Step 3: Subsequent Logins

For every login after setup:

Solve the CAPTCHA.
Enter the 6-digit code from Google Authenticator.
Provide your cluster password.

Step 4: Resetting 2FA (e.g., lost device)

If you need to reconfigure 2FA:

Generate a new secret key and QR code
Update ~/.google_authenticator
Enable security options (recommended: yes to all)

Important: Without your phone or backup codes, you cannot log in. Contact support immediately if both are lost.

Connecting to PARAM Shakti

From Windows

Use one of the following SSH clients:

MobaXterm (recommended for first-time users) — Professional Edition available
PuTTY (free and open-source)

Connection string: username@paramshakti.iitkgp.ac.in

During login, you'll be prompted for: CAPTCHA → 2FA code → password.

From Linux or macOS

Use the built-in SSH client:

ssh username@paramshakti.iitkgp.ac.in

From Outside IIT Kharagpur Campus Network

Direct external SSH access is disabled. You must first connect via the IIT Kharagpur VPN.

Request VPN access by emailing helpdesk@cic.iitkgp.ac.in or shaktisupport@iitkgp.ac.in (attach the completed VPN-Access.pdf form).
Once approved, connect to the VPN.
Then SSH using the internal IP:
ssh username@10.171.17.201

Account Management

Password Policy

All passwords must adhere to the following:

Minimum 13 characters
At least one uppercase letter
At least one lowercase letter
At least one digit
At least one special character (e.g., !@#$%^&*)
Password rotation every 90 days

Changing Your Password

From the login node, run:

passwd
# Follow the prompts to set a new compliant password.

[username@login06 ~]$ passwd
########################################
Password Requirements:
  Minimum length: 13 characters
  At least 1 uppercase letter
  At least 1 lowercase letter
  At least 1 number
  At least 1 special character (e.g., !@#$%^&*)
########################################

Changing password for user username.
(current) LDAP Password: _

Forgot Password?

Raise a request for HPC password change through the login portal: https://hpc.iitkgp.ac.in/hpc/app

02

Job Scheduling

This information is applicable for IITKGP internal users. Other users in NSMapp, NSMext, etc., are requested to contact CDAC for information on storage, charging policy, and queuing priority.

Scheduler

PARAM Shakti uses Slurm 22.05.09 (open-source) as the workload manager for the HPC facility. The following partitions (queues) have been defined to meet different computational requirements.

Partition	Min–Max Cores / Nodes per Job	Max Walltime	Priority	Comments
Shared	1–36 cores	03 days	200	Compute nodes only. Node sharing is allowed between different jobs.
Medium	1–10 nodes	03 days	200	Compute and high-memory nodes. Nodes allocated exclusively; node sharing not allowed.
Large	1–10 nodes	07 days	10	Compute and high-memory nodes. Intended for long-running jobs; node sharing not allowed.
GPU	GPU nodes only. Configuration remains unchanged.	—	—	—

Partition Details

Shared Partition: Designed for serial and OpenMP jobs. Users may request a minimum of 1 core and a maximum of 36 cores. The maximum walltime is 3 days.
Medium Partition: Suitable for single-node and multi-node jobs. Entire nodes are allocated exclusively. Users may request between 1 and 10 nodes. The parameter --ntasks-per-node=40 must not be changed. Maximum walltime is 3 days.
Large Partition: Similar to the medium partition but intended for longer jobs with a maximum walltime of 7 days. Due to its lower priority, this partition should be used only when longer walltime is required.
GPU Partition: Dedicated to GPU-based workloads. Configuration remains unchanged.

Types of Nodes

Compute Nodes (cn): The system comprises 384 compute nodes, labelled cn001 to cn384. These nodes are distributed across the shared and medium/large partitions based on historical usage and job queue demand.
High-Memory Nodes (hm): A total of 36 high-memory nodes, labelled hm001 to hm036, are available only in the medium and large partitions. To request more than 4.3 GB of memory per core, specify either:
- #SBATCH --exclude=cn[085-384]
- #SBATCH --mem-per-cpu=AA G (replace AA with a value between 4 and 18)
GPU Nodes (gpu): The system includes 22 GPU nodes, labelled gpu001 to gpu022. Accessible exclusively through the GPU partition. To request a GPU: #SBATCH --gres=gpu:1

Storage Policy

File System	Quota	Retention Period
/home	Soft Limit: 40 GB Hard Limit: 50 GB *Except for UG students	Unlimited
/scratch	Soft Limit: 2 TB	60 days Files older than the retention period will be deleted

Users can check their /home and /scratch quota using the myquota command.

[username@login05 ~]$ myquota
Filesystem    used    quota   limit   grace   files   quota   limit   grace
   /home       68k     40G     50G       -       17       0       0       -
/scratch        4k      2T      0k       -        1       0       0       -
[username@login05 ~]$

Usage Instructions

/home/<username>/ — Used for installing applications.
/scratch/<username>/ — Used for project / research data.

Users are advised to maintain local backups of their data. Storage and charging policies are subject to change.

Data Safety

Users are advised to keep a backup of their data locally. Once the project/research work is completed, transfer the data from PARAM Shakti to your local system using the commands shown in the File Transfers section. Users' data stored on the scratch directory on PS is NOT backed up or archived by the system administration. The PS administration is also not responsible for restoring damaged or lost files. Backing up and archiving data is the responsibility of the user and his/her Project Guide/Adviser.

03

Job Submission

Serial

Script for a Single Core Serial Job

#!/bin/bash
#SBATCH -J job_name              # name of the job
#SBATCH -p shared                # partition: available options "shared"
#SBATCH -n 1                     # no of processes
#SBATCH -t 01:00:00              # walltime HH:MM:SS, Max 72:00:00

# list of modules to load, e.g.:
# module load apps/lammps/12.12.2018/intel

exe=name_executable
$exe   # specify command-line options after $exe

OpenMP

Script for a Single Node OpenMP Job

#!/bin/bash
#SBATCH -J job_name              # name of the job
#SBATCH -p shared                # partition: "shared"
#SBATCH -N 1                     # no of nodes
#SBATCH -n 1                     # no of processes/tasks
#SBATCH --cpus-per-task=10       # no of threads per process
#SBATCH -t 01:00:00              # walltime HH:MM:SS, Max 72:00:00

# module load apps/lammps/12.12.2018/intel

exe=name_executable
export OMP_NUM_THREADS=$SLURM_CPUS_PER_TASK
$exe

MPI

Script for a Multinode MPI Job

#!/bin/bash
#SBATCH -J job_name                # name of the job
#SBATCH -p medium                  # partition: "large" or "medium"
#SBATCH -N 2                       # no of nodes
#SBATCH --ntasks-per-node=40       # tasks per node
#SBATCH -t 01:00:00                # walltime; Max 72:00:00 (medium), 168:00:00 (large)

# module load apps/lammps/12.12.2018/intel

exe=name_executable
mpirun -bootstrap slurm -n $SLURM_NTASKS $exe

Please try to use a number of MPI tasks ($SLURM_NTASKS) that is a multiple of 40 to avoid node sharing between different users and to increase overall cluster utilisation.

MPI + OpenMP (Hybrid)

Script for a Multinode MPI+OpenMP (Hybrid) Job

#!/bin/bash
#SBATCH -J job_name                # name of the job
#SBATCH -p medium                  # partition: "medium" or "large"
#SBATCH -N 2                       # no of nodes
#SBATCH --ntasks-per-node=40       # tasks per node
#SBATCH --cpus-per-task=1          # threads per task (for OpenMP)
#SBATCH -t 01:00:00                # walltime

# module load apps/lammps/12.12.2018/intel

exe=name_executable
export OMP_NUM_THREADS=$SLURM_CPUS_PER_TASK
mpirun -bootstrap slurm -n $SLURM_NTASKS $exe

General Procedure — Batch Script & Job Submission

PARAM Shakti provides a well-defined software environment to compile and run applications using Environment Modules and Spack. These tools ensure that the correct versions of compilers, libraries, and applications are available during a user session and within SLURM batch jobs.

Using Environment Modules

module avail                          # list all available modules
module load intel/2018.0.1.163        # load the Intel compiler
module unload intel/2018.0.1.163      # remove Intel compiler from environment
module show intel/2018.0.1.163        # display module environment changes

Using Spack

Spack is an alternative and more flexible package manager that allows users to install and manage multiple versions of compilers, libraries, and applications with customised build options. Required packages must be loaded in the environment before launching the job.

spack list                    # list all available packages
spack find                    # list all installed packages
spack install <package>       # install the specified package
spack load <package>          # load the installed package
spack unload <package>        # unload the package
spack spec <package>          # display dependency and build configuration

Sample Slurm Job Script

#!/bin/bash
#SBATCH -J lammps-mpi                  # job name
#SBATCH -o %j-out-myjob                # stdout output file
#SBATCH -e %j-err-myjob                # stderr error file
#SBATCH -p shared                      # partition: shared, medium, large, gpu
#SBATCH -n 3                           # total MPI tasks
#SBATCH -c 2                           # threads per task
#SBATCH -t=00:10:00                    # walltime (max duration)
#SBATCH --mem=23000                    # min memory per node in MB
#SBATCH --mem-per-cpu=6000M            # min memory per allocated CPU
#SBATCH --mail-user=abc@iitkgp.ac.in  # email for job status
#SBATCH --mail-type=ALL                # send mail for all event types

if [ -n "$SLURM_CPUS_PER_TASK" ]; then
  omp_threads=$SLURM_CPUS_PER_TASK
else
  omp_threads=1
fi

# module load apps/lammps/7Aug19/intel

exe=name_executable
export OMP_NUM_THREADS=$omp_threads
mpirun -bootstrap slurm -n $SLURM_NTASKS $exe

SLURM Parameter Reference

Job flags are used with sbatch. Syntax in a script: #SBATCH <flag>. Some flags also apply to srun and salloc. See man sbatch for full details.

Resource	Flag Syntax	Description
partition	`--partition=partition_name` or `-p`	Partition (queue) for jobs.
time	`--time=01:00:00` or `-t`	Time limit for the job.
Total MPI tasks	`--ntasks=8` or `-n 8`	Total MPI tasks required by the job.
Threads per MPI task	`--cpus-per-task=4` or `-c 4`	Cores per MPI task.
GPU	`--gres=gpu:N` where N=1 or 2	Request use of GPUs on compute nodes.
error file	`--error=err.out`	Job error messages written to this file.
job name	`--job-name="lammps"`	Name of job.
output file	`--output=lammps.out`	Name of file for stdout.
email address	`--mail-user=username@iitkgp.ac.in`	User's email address.
memory	`--mem=2300`	Memory required per node in MB.

Submit the Job

Once the required modules or Spack packages are loaded, prepare a SLURM batch script and submit with sbatch.

$ sbatch slurm-job.sh
  Submitted batch job 106

$ squeue
JOBID PARTITION NAME  USER  ST TIME NODES NODELIST(REASON)
  150 standard  simple user1  R 0:31     1 atom01

Sample batch scripts are available at /home/iitkgp/slurm-scripts. For more information refer to the SLURM Documentation .

Running Interactive Jobs

The following command requests a single core for one hour with the default amount of memory:

$ srun --nodes=1 --ntasks-per-node=1 --time=01:00:00 --pty bash -i

04

Job Control

Controlling Jobs

Command	Explanation
`squeue`	View job and job step information for jobs managed by SLURM.
`scontrol show node`	Show detailed information about compute nodes.
`scontrol show partition <partition name>`	Show detailed information about a specific partition/queue.
`scontrol show job <job ID>`	Show detailed information about a specific job (or all jobs if no ID given).
`sinfo`	View information about Slurm nodes and partitions/queues.
`scancel <job ID>`	Kill a job. Users can kill their own jobs; root can kill any job.
`scontrol hold <job ID>`	Hold a job.
`scontrol release <job ID>`	Release a job.
`sbalance`	Check available account balance.

Sample Command Outputs

List Jobs

$ squeue
  JOBID PARTITION NAME     USER  ST TIME NODES NODELIST(REASON)
    106 standard  slurm-jo user1  R 0:04     1 atom01

Get Job Details

$ scontrol show job 106
JobId=106 Name=slurm-job.sh
   UserId=user1(1001) GroupId=user1(1001)
   Priority=4294901717 Account=(null) QOS=normal
   JobState=RUNNING Reason=None Dependency=(null)
   RunTime=00:00:07 TimeLimit=14-00:00:0
   SubmitTime=2013-01-26T12:55:02 StartTime=2013-01-26T12:55:02
   Partition=standard AllocNode:Sid=atom-head1:3526
   NodeList=atom01
   NumNodes=1 NumCPUs=2 CPUs/Task=1
   Command=/home/user1/slurm/local/slurm-job.sh
   WorkDir=/home/user1/slurm/local

Kill a Job

$ scancel 135
$ squeue
  JOBID PARTITION NAME USER ST TIME NODES NODELIST(REASON)

Hold a Job

$ squeue
  JOBID PARTITION     NAME     USER  ST       TIME  NODES NODELIST(REASON)
    139      standard   simple  user1  PD       0:00      1 (Dependency)
    138      standard   simple  user1   R       0:16      1 atom01
$ scontrol hold 139
$ squeue
  JOBID PARTITION     NAME     USER  ST       TIME  NODES NODELIST(REASON)
    139      standard   simple  user1  PD       0:00      1 (JobHeldUser)
    138      standard   simple  user1   R       0:32      1 atom01

Release a Job

$ scontrol release 139
$ squeue
  JOBID PARTITION     NAME     USER  ST       TIME  NODES NODELIST(REASON)
    139      standard   simple  user1  PD       0:00      1 (Dependency)
    138      standard   simple  user1   R       0:46      1 atom01

View Available Partitions / Node Status

$ sinfo -s
PARTITION     AVAIL   TIMELIMIT   NODES(A/I/O/T)  NODELIST
standard         up 3-00:00:00    32/356/54/442  cn[001-384],gpu[001-022],hm[001-036]
gpu              up 3-00:00:00        0/21/1/22  gpu[001-022]
hm               up 3-00:00:00        0/35/1/36  hm[001-036]
standard-low*    up 3-00:00:00    32/356/54/442  cn[001-384],gpu[001-022],hm[001-036]

05

SLURM Account Coordinator

The Paramshakti HPC system treats each faculty adviser as the head of a research group. Each research group has a Slurm "account" that all members are part of. Each faculty adviser is set as an "account coordinator" who can modify settings for users in that account, and can hold and cancel jobs submitted by other members.

Controlling Jobs and Shares — Account Coordinator Commands

Command	Explanation
`squeue -A <account>`	List jobs run under the account.
`squeue -u <student>`	List jobs run by a specific student account.
`scancel -u <student>`	Kill all jobs by a student account.
`scancel -A <account>`	Kill all jobs under the account.
`scontrol <hold\|release\|unhold> <jobid>`	Hold / Release / Unhold a job.
`sacctmgr modify user <student> where Account=prj_account set GrpTRESMins=cpu=6000000`	Restrict user to 6,000,000 CPU-core-mins (100,000 SU) against the project account.
`sacctmgr modify user <student> where Account=prj_account set GrpCPUs=64`	Limit the number of processor cores for a user across all partitions. Set to -1 to clear.
`sacctmgr modify user where user=<student> where Account=prj_account set Fairshare=10`	Adjust the Rawshare of a user relative to other members. All new users default to Rawshare=1.
`sbalance`	Check available account balance.

Verify Users Associated with an Account

To verify users associated with a test faculty adviser account called testfac1 use the command below. Here four test users along with the faculty adviser (total five members) are associated with the account:

[testfac1@vm01 ~]$ sacctmgr show assoc where Account=testfac1 format=account%15,user%15,qos%25
        Account            User                       QOS
--------------- --------------- -------------------------
       testfac1                                  testfac1
       testfac1        testfac1                  testfac1
       testfac1       testuser1                  testfac1
       testfac1       testuser2                  testfac1
       testfac1       testuser3                  testfac1
       testfac1       testuser4                  testfac1

View and Change Rawshares / Normalised Shares

[testfac1@vm01 ~]$ sshare -A testfac1 -a -o Account,User,RawShares,NormShares
             Account       User   RawShares  NormShares
-------------------- ---------- ---------- -----------
testfac1                                 1    0.009836
 testfac1              testfac1          1     0.001967
 testfac1             testuser1          1     0.001967
 testfac1             testuser2          1     0.001967
 testfac1             testuser3          1     0.001967
 testfac1             testuser4          1     0.001967

Use the commands below to redistribute the normalised shares of the parent account among all members of the research group (example: ratio 2:3:5:0:1):

[testfac1@vm01 ~]$ sacctmgr modify user where user=testfac1  set Fairshare=2
[testfac1@vm01 ~]$ sacctmgr modify user where user=testuser1 set Fairshare=3
[testfac1@vm01 ~]$ sacctmgr modify user where user=testuser2 set Fairshare=5
[testfac1@vm01 ~]$ sacctmgr modify user where user=testuser3 set Fairshare=0
[testfac1@vm01 ~]$ sacctmgr modify user where user=testuser4 set Fairshare=1

[testfac1@vm01 ~]$ sshare -a -l -A testfac1 -o Account,User,RawShares,NormShares,FairShare
             Account       User   RawShares  NormShares  FairShare
-------------------- ---------- ---------- ----------- ----------
testfac1                                 1    0.009836    1.000000
 testfac1              testfac1          2     0.001788   1.000000
 testfac1             testuser1          3     0.002683   1.000000
 testfac1             testuser2          5     0.004471   1.000000
 testfac1             testuser3          0     0.000000   0.000000
 testfac1             testuser4          1     0.000894   1.000000

Job Priority

Job priority is a weighted sum of several factors including job size, queue time, and fairshare. The formula is:

Job_priority =
     site_factor +
     (PriorityWeightAge)       * (age_factor) +
     (PriorityWeightAssoc)     * (assoc_factor) +
     (PriorityWeightFairshare) * (fair-share_factor) +
     (PriorityWeightJobSize)   * (job_size_factor) +
     (PriorityWeightPartition) * (partition_factor) +
     (PriorityWeightQOS)       * (QOS_factor) +
     SUM(TRES_weight_cpu * TRES_factor_cpu, ...)
     - nice_factor

See the SLURM priority documentation for full details. To print job priorities for specific users:

$ sprio --users=testuser1,testuser2
   JOBID      USER    PRIORITY    AGE  FAIRSHARE   JOBSIZE  PARTITION  QOS
   65548  testuser1      62079      1      51077      1000      10000    0
   65549  testuser2      62080      1      51078      1000      10000    0

To print configured weights for each priority component:

$ sprio -w
 JOBID PARTITION  PRIORITY SITE   AGE  FAIRSHARE  JOBSIZE  PARTITION  QOS  TRES
 Weights               1  10000  100000      1000    15000     1000  CPU=1000,Mem=5000

Fairshare Factor

Fairshare is essentially Shares / Usage. Usage is based on CPU-time allocated to prior jobs and decays over time so that recent usage is weighted more heavily. Within an account, each user's slice of the pie is shares_self / sum(shares_self_plus_siblings). To view level fairshare within an account:

sshare -laA youraccount

# Level FS = Norm Shares / Effectv Usage
# Norm Shares      = Raw Shares / sum of (self + siblings) Raw Shares
# Effective Usage  = Raw Usage / account's Raw Usage

06

Software Available

Installed Applications & Libraries

Following is the list of applications and libraries installed on PARAM Shakti. This list may not be complete. Use module avail to see the latest list of available software on the system.

Category	Sub-Category	Applications / Tools
HPC Applications	Bio-informatics	MUMmer, HMMER, MEME, PHYLIP, mpiBLAST, ClustalW
HPC Applications	Molecular Dynamics	NAMD (CPU/GPU), LAMMPS, GROMACS
HPC Applications	Material Modelling / Quantum Chemistry	Quantum-Espresso, Abinit, CP2K, NWChem
HPC Applications	CFD	OpenFOAM, SU2
HPC Applications	Weather / Ocean / Climate	WRF-ARW, WPS (WRF), ARWPost (WRF), RegCM, MOM, ROMS
Deep Learning Libraries	—	cuDNN, TensorFlow, TensorFlow (Intel Python), TensorFlow (GPU), Theano, Caffe, Keras, NumPy, SciPy, Scikit-Learn, PyTorch
Dependency Libraries	—	NetCDF, PNETCDF, Jasper, HDF5, Tcl, Boost, FFTW
Compilers	—	CUDA, Intel compiler suite, GCC, IntelMPI, OpenMPI, PGI

Software Installation Requests

Open-Source Software

Not all open-source software/libraries will be installed in the central repository. If the software is being used by at least a few research groups in our institute, open a support ticket and provide: a link to the download page and installation instructions. The PS technical support team may request additional information if required.

Commercial Software

If the license agreement permits institutional-wide usage, open a support ticket and provide: a link to the download page, installation instructions, and the license agreement document. The license will be verified by the PS technical support team before proceeding.

Any software/library may be installed by the user in their home directory on PS, provided it does not violate the software license agreement. If assistance is required, contact the PS technical support team via the support portal . Support will be provided on a best-effort basis.

07

File Transfers

This information is applicable for IITKGP internal users. Other users (NSMapp, NSMext, etc.) are requested to contact CDAC for information on storage, charging policy, and queuing priority.

Transferring Files Between Local Machine and HPC Cluster

Users need to have their data and applications on PARAM Shakti. Two directories are available to each user:

/home/<username>/    # install applications here
/scratch/<username>/ # store project/research data here

Storage is subject to quotas (see Job Scheduling → Storage Policy). Use the following scp commands to transfer files:

# Local → HPC
[localhost]$ scp -r /mydata/dir1 saurabh@paramshakti.iitkgp.ac.in:/home/saurabh

# HPC → Local
[localhost]$ scp -r saurabh@paramshakti.iitkgp.ac.in:/home/saurabh /mydata/dir1

Users are advised to keep a local copy of their data once the project/research work is completed.

File Transfer Tools

WinSCP (Windows)

This popular free GUI tool is widely used to transfer data from Windows to Linux. Download it from winscp.net .

Command Prompt / Terminal (Linux & macOS)

SCP is available natively on all Unix/Linux systems. Use the -o UserKnownHostsFile=/dev/null option to avoid SSH key errors, and -r to copy directories recursively.

scp -r -o UserKnownHostsFile=/dev/null <Username>@paramshakti.iitkgp.ac.in:/home/<Username>/perl5 ./

[username@local ~]$ scp -r -o UserKnownHostsFile=/dev/null username@paramshakti.iitkgp.ac.in:/home/username/perl5 ./
The authenticity of host 'paramshakti.iitkgp.ac.in (10.171.17.201)' can't be established.
ECDSA key fingerprint is SHA256:xN9lbdCx4+ywHnsuK1McWGguquHAWCxBdSbI1mNqtlY.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'paramshakti.iitkgp.ac.in,10.171.17.201' (ECDSA) to the list of known hosts.
If you truly desire access to this host, then you must indulge me in a simple challenge.
----------------------------------------------------------------------
  [solve the CAPTCHA shown, then enter your password]
----------------------------------------------------------------------
Password: _
[username@local ~]$ ls -ld perl5
drwxrwxr-x 2 username username 10 Mar 19 17:04 perl5

File Transfer from Outside IIT Kharagpur Campus

Modern Windows, Linux, and macOS systems provide a built-in SCP client. Open the terminal and provide port number 4422 in the scp command:

# General syntax
scp -P 4422 -o UserKnownHostsFile=/dev/null -r [source_folder] [username]@[hostname]:[destination]

# Example: local folder 'iitkgp' to home directory on PARAM Shakti
user1@login01$ scp -P 4422 -o UserKnownHostsFile=/dev/null -r iitkgp user1@paramshakti.iitkgp.ac.in:/home/user1/

C:\Users\Admin1>scp -P 4422 -o UserKnownHostsFile=/dev/null -r test username@paramshakti.iitkgp.ac.in:/home/username/
The authenticity of host '[paramshakti.iitkgp.ac.in]:4422 ([10.171.17.201]:4422)' can't be established.
ECDSA key fingerprint is SHA256:xN9lbdCx4+ywHnsuK1McWGguquHAWCxBdSbI1mNqtlY.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '[paramshakti.iitkgp.ac.in]:4422,[10.171.17.201]:4422' (ECDSA) to known hosts.
If you truly desire access to this host, then you must indulge me in a simple challenge.
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  [solve the CAPTCHA shown, then enter your password]
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Password: _

C:\Users\Admin1>

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