What is the difference between
install -c and
cp? Most installations tend to use
install -c, but from the
man page it doesn't sound like it does anything different than
cp (except maybe the ability to also set permissions). When should I use
install -c and when
One significant difference is that cp truncates the destination file and starts copying data from the source into the destination file.
install, on the other hand, removes the destination file first.
This is significant because if the destination file is already in use, bad things could happen to whomever is using that file in case you
cp a new file on top of it. e.g. overwriting an executable that is running might fail. Truncating a data file that an existing process is busy reading/writing to could cause pretty weird behavior. If you just remove the destination file first, as install does, things continue much like normal - the removed file isn't actually removed until all processes close that file.
Technically, the difference between
install -c and
cp is that
install sets the permissions of the target file to
cp preserves the permissions of the source file minus the umask. These default behaviors are useful in different situations. Obviously, with all the options that both
install offer nowadays, the functionalities have converged.
install is commonly used in makefiles,
cp everywhere else. This distinction is occasionally useful because some operating systems or installation systems allow you to hook into the
install program to register the installed packages. Modern package management systems make this kind of obsolete, but some people still use it. Also, the possibility to set the target file permissions in the same go is very convenient.
install utility, at its base, is a fancy
cp. But as a tool specifically do installs it contains a few features that
cp doesn't. My
/usr/bin/install from GNU coreutils not only copies, but also can change perms/ownership as arg flags (saving
chmod invocations) an option to strip debug info (saving a
strip invocation) and also some mojo for SELinux contexts.
It just provides convenience actions useful for software installs. None are life changing, all are useful, and make your scripts cleaner.