What is the difference between just setting a command on Linux and entering the same command after executing '/ bin / sh'?

Question

I understand that /bin/shthis is a shell that executes the commands that I typed. But the fact is that although I do not type /bin/sh, I can enter any command I want.

I heard that when a cracker wants to attack someone, he or she usually wants to get it /bin/sh. In particular, I heard /bin/shmentioned in combination with buffer overflows and remote shells, and that crackers can use programs using malicious code executed with / bin / sh, for example exec ("bin/sh", ~something, something);.

I wonder why he or she is trying to “receive” /bin/shor execute it.

I am also not sure of the difference between simply writing a command and entering the same command after execution /bin/sh, as shown in this interaction with the terminal:

johndoe@localhost $ pwd
/home/johndoe
johndoe@localhost $ /bin/sh
sh-3.2 $ pwd
/home/johndoe
sh-3.2 $ whoami
johndoe
sh-3.2 $ 

Although I am not executing /bin/sh, I can still enter any command I want to enter. So why and when will crackers want to use /bin/sh?

Answer 1

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Answer 2

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, :

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Answer 3

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