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Linux Notes

Bash test command

Use [[ ... ]] instead of [ ... ] to test a condition in Bash. The latter is poor in function and unmentioned in the official GNU Bash document at all.

Disable password login for user

passwd -l {username}

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Distributed Model Training in PyTorch DDP

Prerequisites

Ensure GPU device is ready

Check GPU by lspci

Ensure enough free disk space

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PowerShell vs Bash in Examples

Key different points

• Bash commands output strings while PS commands output objects!

Examples

The following standard aliases in PowerShell are used:

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WSL Settings and Issue Fixes

Enable systemd

1. Get the latest version WSL from the Windows Store

2. Ensure /etc/wsl.conf has

[boot]

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cgroup and systemd

cgroup

"The control groups, abbreviated as cgroups in this guide, are a Linux kernel feature that allows you to allocate resources — such as CPU time, system memory, network bandwidth, or combinations of these resources — among hierarchically ordered groups of processes running on a system."

Check the cgroups by systemd-cgls.

Resource controller

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Setup Service Fabric Development Environment on Linux

The official document at https://learn.microsoft.com/en-us/azure/service-fabric/service-fabric-get-started-linux is problematic (ESPECIALLY, DO NOT follow the instruction in that document to install Docker!). Here're the correct steps.

Prerequisites

1. Check if your Linux distro and version are supported at https://learn.microsoft.com/en-us/azure/service-fabric/service-fabric-versions#supported-linux-versions-and-support-end-date
2. Setup Docker as instructed by https://docs.docker.com/engine/install/ubuntu

Install Service Fabric SDK

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Linux Linkers and Loaders

Tools

• ldconfig
• ld.so
• ld
• ldd

ldconfig

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Proxy

Proxy vs VPN

• Proxy is not VPN.
• An application could provide an option to use a proxy, by a command line parameter, or an environment variable. Or it could provide no option for proxy at all!
• VPN is an easy way to "proxy" the whole system without any application specific settings.

A proxy could use SOCKS or HTTP protocol.

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SSH Port Forwarding

Refer to https://help.ubuntu.com/community/SSH/OpenSSH/PortForwarding

Local Port Forwarding

man:

-L [bind_address:]port:remote_socket

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Autoscale in CycleCloud

What is CycleCloud

CycleCloud is a product that

• makes it easy to create and manage HPC computer clusters
• is open to integrate with various HPC schedulers, like PBS, Slurm, HPC Pack, etc.
• is deployed by user