# Understanding the Core Files
$ ls -l /etc/DIR_COLORS*
-rw-r--r-- 1 root root 4433 Apr  5  2018 /etc/DIR_COLORS
-rw-r--r-- 1 root root 4339 Apr  5  2018 /etc/DIR_COLORS.xterm

Linux terminal colors for ls command are controlled through these mechanisms:

• System-wide: /etc/DIR_COLORS (generic) and /etc/DIR_COLORS.xterm (terminal-specific)
• User-specific: ~/.dir_colors (overrides system settings)

For PuTTY with black background, modify the dark blue directory entry:

# Backup original file
$ cp /etc/DIR_COLORS ~/.dir_colors

# Edit the configuration
$ nano ~/.dir_colors

# Change this line (original):
DIR 01;34  # directory

# To one of these alternatives:
DIR 01;36  # cyan
DIR 01;33  # yellow
DIR 01;35  # magenta

Different terminals may need different configurations:

# For xterm-type terminals
TERM xterm
DIR 01;36

# For rxvt-type terminals
TERM rxvt
DIR 01;33;47

After modifying the configuration:

# Load new settings
$ eval $(dircolors ~/.dir_colors)

# Test immediately
$ ls

To make changes permanent, add this to your ~/.bashrc:

# Persistent dircolors configuration
if [ -f ~/.dir_colors ]; then
    eval "$(dircolors ~/.dir_colors)"
fi

Full syntax for color definitions:

# Format: TYPE ATTRIBUTES;FOREGROUND;BACKGROUND
# Example for executable files:
EXEC 01;32  # bright green

Common attributes (first number):

• 00 = none
• 01 = bold
• 04 = underlined
• 05 = flashing
• 07 = reverse

For quick temporary changes:

# Set directly in terminal
$ export LS_COLORS="di=1;36:ex=1;32:*.txt=1;33"

This changes directories to cyan, executables to green, and text files to yellow.

# Check current LS_COLORS value
$ echo $LS_COLORS

# Verify terminal type
$ echo $TERM

# Reload bash configuration
$ source ~/.bashrc

---

When using Putty with a black background, the default dark blue directory colors in ls output become nearly unreadable. This isn't just a Putty issue - many terminal emulators and dark themes face similar visibility challenges with the default Linux color scheme.

The system uses two key files for color configuration:

/etc/DIR_COLORS       # System-wide defaults
~/.dir_colors         # User-specific overrides

For Xterm-based terminals (including Putty), the system may also reference:

/etc/DIR_COLORS.xterm

First, copy the default configuration to your home directory:

cp /etc/DIR_COLORS ~/.dir_colors

Then edit the file to modify the problematic entries. The key lines to change:

DIR 01;34   # Change from dark blue (34) to something more visible

For dark backgrounds, these alternatives work well:

DIR 01;36   # Cyan
DIR 01;33   # Yellow
DIR 01;35   # Magenta
DIR 01;32   # Green

After saving the file, either:

• Start a new terminal session, or
• Run: eval $(dircolors ~/.dir_colors)

For Putty, you might also need to:

1. Configure ANSI colors in Putty's settings
2. Ensure "Use system colours" is unchecked
3. Adjust individual color values in Window → Colours

If colors don't change as expected:

# Verify file parsing
dircolors --print-database ~/.dir_colors

# Check environment variables
echo $LS_COLORS

Add this to your ~/.bashrc:

if [ -f ~/.dir_colors ]; then
    eval $(dircolors ~/.dir_colors)
fi

Here's a sample .dir_colors for dark terminals:

# Avoid dark blue and black
DIR 01;36
LINK 01;35
SOCK 01;33
FIFO 01;33
EXEC 01;32

# File types
.txt 00;32
.md 00;32
.conf 00;33