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Linux for Production Support Ch 2 / 32 Beginner 🪟 Windows → Linux

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Vijay learns the filesystem

No C: drive, no backslashes — how Linux organises everything

⏱ 11 min 6 commands 5 takeaways

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In this chapter

Vijay

Windows support engineer, week 1 on Linux

The story

On day 2, Vijay needed to find the application config file. On Windows he knew where to look: Program Files, AppData, or the Registry. On Linux he had no idea.

His colleague Priya explained the Linux filesystem layout in 10 minutes.

EVERYTHING IS UNDER / (called root)

On Windows you have C: D: E: separate drive letters. On Linux everything is one tree starting from /.

Windows: C:\Windows\System32
Linux:   /usr/lib or /usr/bin

Windows: C:\Program Files\Apache\
Linux:   /opt/apache/ or /usr/local/apache/

Windows: C:\Windows\Temp
Linux:   /tmp

Windows: C:\Users\vijay\
Linux:   /home/vijay or ~

THE KEY DIRECTORIES:

/etc contains ALL config files. Think of it as the Registry but as plain readable text files.

ls /etc/                    # see all config files
cat /etc/hosts              # like Windows hosts file (exact same purpose!)
cat /etc/hostname           # the machine name
cat /etc/os-release         # Linux version info
ls /etc/nginx/              # nginx config directory
ls /etc/systemd/system/     # service definitions (like Services.msc entries)

/var/log contains ALL log files. Think Event Viewer but as text files.

ls /var/log/                # see all log categories
tail -f /var/log/syslog     # system log (like Windows System event log)
tail -f /var/log/auth.log   # login attempts (like Windows Security event log)
ls /var/log/nginx/          # nginx access and error logs

/opt is where third-party applications live. Like Program Files but simpler.

ls /opt/                    # see installed apps
ls /opt/tomcat/             # Tomcat installation

/home is user home directories. Like C:\Users\

ls /home/                   # see all users
cd ~                        # go to your own home directory

NO DRIVE LETTERS - MOUNT POINTS INSTEAD

On Windows, a second disk becomes D:. On Linux, it gets mounted as a folder:

df -h
# /dev/sda1  50G  30G  20G  60%  /           (main disk)
# /dev/sdb1 200G  45G 155G  22%  /var        (second disk mounted as /var)
# /dev/sdc1   2T 500G 1.5T  25%  /data       (data disk)

FILE PATHS - FORWARD SLASHES, NO BACKSLASHES

Windows: C:\Users\vijay\Documents\report.txt
Linux:   /home/vijay/documents/report.txt

Windows: .\logs\app.log    (relative path)
Linux:   ./logs/app.log    (relative path, same concept, forward slash)

HIDDEN FILES start with a dot:

ls /home/vijay/             # shows normal files
ls -la /home/vijay/         # shows hidden files too
cat /home/vijay/.bashrc     # user shell config

PERMISSIONS:

ls -la /opt/myapp/config.xml
# -rw-r--r-- 1 tomcat appteam 4096 Mar 16 config.xml
#
# - = file (d would be directory)
# rw- = owner can read and write
# r-- = group can read only
# r-- = everyone else can read only

chmod 644 config.xml        # set permissions (like Security tab in Properties)
chown tomcat:appteam file   # change owner (like Change Owner in Properties)
sudo chmod 755 /opt/myapp/  # need sudo to change others files

Vijay found the app config in /etc/myapp/app.conf in under a minute once he knew the structure. All configs in /etc, all logs in /var/log, all apps in /opt.

Key takeaways

/etc contains all config files — think of it as the Registry but readable text files you can cat, grep, and diff

/var/log contains all log files — this is your Event Viewer, organised by application and service

/opt is where third-party apps live (like Program Files), /home is user folders (like C:/Users)

Linux uses forward slashes not backslashes, and hidden files start with a dot

df -h shows all mounted filesystems — there are no drive letters, disks mount as folders

Commands from this chapter

$ ls /etc/

See all config files — the Linux equivalent of the Registry

$ cat /etc/hosts

Same as Windows hosts file — maps hostnames to IPs

$ ls /var/log/

See all log directories — your Event Viewer in text form

$ which programname

Find where a program is installed, like where.exe on Windows

$ ls -la /home/vijay/

List all files including hidden dot files

$ df -h

See all mounted filesystems and which disks are attached