: Legitimate educational PDFs are rarely password-protected or bundled with unrelated software.
You can purchase affordable physical or authorized digital copies (e-books) through major retail platforms like Amazon, Flipkart, or the official publisher, BPB Publications. or the official publisher
: If you are looking for free resources on Unix/Linux shell programming, consider authoritative documentation like the GNU Bash Manual TLDP Bash Guide for Beginners free, open-source books on Unix programming that are legally available? or the official publisher