Add dns for WSL

wsl_fix_dns.sh

#!/bin/bash

RESOLV_CONF="/etc/resolv.conf"
NEW_NAMESERVERS=(
    "nameserver 45.90.28.0"
    "nameserver 45.90.30.0"
    "nameserver 208.67.222.222"
    "nameserver 208.67.220.220"
    "nameserver 8.8.8.8"
    "nameserver 1.1.1.1"
)
MARKER_COMMENT="# Added by custom script" # Optional: To prevent adding multiple times

# --- Check for root privileges ---
if [[ $EUID -ne 0 ]]; then
   echo "This script must be run as root"
   exit 1
fi

# --- Check if file exists ---
if [[ ! -f "$RESOLV_CONF" ]]; then
    echo "Error: $RESOLV_CONF not found."
    exit 1
fi

# --- Optional: Check if already added ---
if grep -qF "$MARKER_COMMENT" "$RESOLV_CONF"; then
    echo "Nameservers seem to be already added (marker found). Exiting."
    exit 0
fi
# More robust check (optional): Check for the first specific IP
# first_new_ns=$(echo "${NEW_NAMESERVERS[0]}" | awk '{print $2}')
# if grep -q "nameserver $first_new_ns" "$RESOLV_CONF"; then
#    echo "First new nameserver (${first_new_ns}) already found. Exiting to prevent duplicates."
#    exit 0
# fi

# --- Prepare the nameserver block ---
ns_block=""
if [[ -n "$MARKER_COMMENT" ]]; then
  ns_block+="$MARKER_COMMENT\n"
fi
for ns in "${NEW_NAMESERVERS[@]}"; do
    ns_block+="$ns\n"
done
# Remove trailing newline
ns_block=${ns_block%\\n}

# --- Use awk to insert the block ---
awk -v ns="$ns_block" '
BEGIN { inserted = 0 }
# Print comments and empty lines directly
/^\s*#/ || /^\s*$/ { print; next }
# If not a comment/empty and not inserted yet, print new servers first
!inserted {
    print ns
    inserted = 1
}
# Print the current non-comment line (either after insertion or if already inserted)
{ print }
# Handle case where file only has comments/empty lines
END {
    if (!inserted) {
        print ns
    }
}
' "$RESOLV_CONF" > "${RESOLV_CONF}.tmp" && mv "${RESOLV_CONF}.tmp" "$RESOLV_CONF"

if [[ $? -eq 0 ]]; then
    echo "Successfully updated $RESOLV_CONF"
    # Optional: Set permissions if needed (mv usually preserves them)
    # chmod 644 "$RESOLV_CONF"
    # chown root:root "$RESOLV_CONF" # Or appropriate owner/group
else
    echo "Error updating $RESOLV_CONF"
    rm -f "${RESOLV_CONF}.tmp" # Clean up temp file on failure
    exit 1
fi

exit 0

wsl_fix_dns_sen.sh

#!/bin/bash

RESOLV_CONF="/etc/resolv.conf"
NEW_NAMESERVERS=(
    "nameserver 45.90.28.0"
    "nameserver 45.90.30.0"
    "nameserver 208.67.222.222"
    "nameserver 208.67.220.220"
    "nameserver 8.8.8.8"
    "nameserver 1.1.1.1"
)
MARKER_COMMENT="# Added by custom script" # Optional: To prevent adding multiple times

# --- Check for root privileges ---
if [[ $EUID -ne 0 ]]; then
   echo "This script must be run as root"
   exit 1
fi

# --- Check if file exists ---
if [[ ! -f "$RESOLV_CONF" ]]; then
    echo "Error: $RESOLV_CONF not found."
    exit 1
fi

# --- Optional: Check if already added ---
if grep -qF "$MARKER_COMMENT" "$RESOLV_CONF"; then
    echo "Nameservers seem to be already added (marker found). Exiting."
    exit 0
fi
# More robust check (optional): Check for the first specific IP
# first_new_ns=$(echo "${NEW_NAMESERVERS[0]}" | awk '{print $2}')
# if grep -q "nameserver $first_new_ns" "$RESOLV_CONF"; then
#    echo "First new nameserver (${first_new_ns}) already found. Exiting to prevent duplicates."
#    exit 0
# fi

# --- Create temporary file ---
TMP_FILE=$(mktemp)
if [[ ! -f "$TMP_FILE" ]]; then
    echo "Error: Could not create temporary file."
    exit 1
fi
# Ensure temp file is removed on exit/error
trap 'rm -f "$TMP_FILE"' EXIT

inserted=0

# --- Process the original file ---
while IFS= read -r line || [[ -n "$line" ]]; do
    # Check if it's a comment or empty line (allowing whitespace before #)
    if [[ "$line" =~ ^[[:space:]]*# ]] || [[ "$line" =~ ^[[:space:]]*$ ]]; then
        echo "$line" >> "$TMP_FILE"
    else
        # First non-comment/non-empty line found, insert new nameservers if not already done
        if [[ $inserted -eq 0 ]]; then
            if [[ -n "$MARKER_COMMENT" ]]; then
              echo "$MARKER_COMMENT" >> "$TMP_FILE" # Add marker
            fi
            for ns in "${NEW_NAMESERVERS[@]}"; do
                echo "$ns" >> "$TMP_FILE"
            done
            inserted=1
        fi
        # Add the current non-comment line
        echo "$line" >> "$TMP_FILE"
    fi
done < "$RESOLV_CONF"

# --- Handle edge case: File only contained comments/empty lines ---
if [[ $inserted -eq 0 ]]; then
     if [[ -n "$MARKER_COMMENT" ]]; then
       echo "$MARKER_COMMENT" >> "$TMP_FILE" # Add marker
     fi
     for ns in "${NEW_NAMESERVERS[@]}"; do
         echo "$ns" >> "$TMP_FILE"
     done
fi

# --- Replace the original file ---
# Get original permissions and ownership (optional but good practice)
ORIG_PERMS=$(stat -c "%a" "$RESOLV_CONF")
ORIG_OWNER=$(stat -c "%u:%g" "$RESOLV_CONF")

# Move temp file to original location (atomic operation)
if mv "$TMP_FILE" "$RESOLV_CONF"; then
    echo "Successfully updated $RESOLV_CONF"
    # Restore permissions and ownership
    chmod "$ORIG_PERMS" "$RESOLV_CONF"
    chown "$ORIG_OWNER" "$RESOLV_CONF"
    # Clean up trap (mv already removed TMP_FILE)
    trap - EXIT
else
    echo "Error: Failed to replace $RESOLV_CONF"
    # Trap will clean up TMP_FILE
    exit 1
fi

exit 0