What does /usr/sbin/install really do?

Question

I'm trying to install discount on my VPS which is based on Solaris and compiling works great after setting some environment variables but the install fails.

So I thought I'd do the install manually, but what does install really do? Is it simply a mv followed by a chmod? Is it magic? That error seems to show that it attempts to do a lot of searching for files all over?

Can I just copy the binary, library and header files as usual?

Googling "install" doesn't give me much relevant information so I appreciate any clarification I can get!

Brakeman

Answer 1

According to man install:

install [OPTION]... [-T] SOURCE DEST`  
install [OPTION]... SOURCE... DIRECTORY  
install [OPTION]... -t DIRECTORY SOURCE...  
install [OPTION]... -d DIRECTORY...  

In the first three forms, copy SOURCE to DEST or multiple SOURCE(s) to the existing DIRECTORY, while setting permission modes and owner/group. In the 4th form, create all components of the given DIRECTORY(ies).

As for the difference to using cp, according to install vs. cp; and mmap, install unlinks the existing file, creating a new one linked to the same spot.

This has the advantage that, if the file you're trying to overwrite is a currently running program, it can continue running, as the file being written is in fact in a new location, and the existing program code is still in the old one.

A cp simply tries to overwrite the existing file, which will fail if the file is locked due to being in use.

Further information

• install Command

Marjie

Yes, well that's how to use it. But what does it really do? Like, behind the scenes. If it only copies a file, why wouldn't the Makefile just use cp? – Sadesadella

I just added a link to install vs. cp; and mmap, which may answer your questions about that. – Poppo

So install is basically a work-around for the fact that BSD doesn't support GNU's cp --remove-destination. – Sew