9
votes
2answers
252 views

What is not shell specific?

Under some answers, I see comments that recommend avoiding shell specific commands in answers. How do I know which commands, operators, etc exist in all shells? Is there a list of standards? man ...
19
votes
5answers
3k views

Why is echo a shell built in command?

$ which echo echo: shell built-in command. $ which ls /bin/ls $ which cat /bin/cat Why is echo not an independent utility like ls, ps, cat etc? Why is it shell specific? Any good reasons?