It's install from the GNU Coreutils

You might think it's a strange choice, boring even. I mean, all it does is copy some files around, right?

Versatility

install can just copy files around, like so:

install -v /path/to/source /path/to/destination

But it can also specify the mode and ownership of the destination:

install -vm2755 -o user -g group /path/to/source /path/to/destination

And it can create parent directories as needed:

install -vDm2755 -o user -g group /path/to/source /path/whose/parents/dont/exist/destination

Oh, and the source can be /dev/stdin:

cat some-file | install -vDm2755 -o user -g group /dev/stdin /path/whose/parents/dont/exist/destination

This can be quite useful for scripting file installs:

curl -fsSL 'https://raw.githubusercontent.com/mwh/dragon/master/dragon.1' |
    sed -e 's/dragon/&-drop/g' |
    install -vDm644 /dev/stdin /usr/share/man/man1/dragon-drop.1

For a sillier example, the tinaries Makefile directs NASM output to /dev/stdout, which is then piped into install, skipping an intermediate file:

nasm -f bin true.asm -o /dev/stdout | install -Dm755 /dev/stdin bin/true

You can also install empty files by using /dev/null as the source:

install -vDm644 /dev/null /etc/subuid
install -vDm644 /dev/null /etc/subgid

Furthermore, you can install many sources to a maybe-nonexistent destination directory like so:

install -vDm644 {LICENSE,*.md} -t /usr/share/doc/some-package/

Flaws

As amazing as install is to use, it's not without its flaws. I wish I could install the same source file to multiple destinations in a single invocation, with something like the following:

install -vDm644 /dev/null /etc/sub{u,g}id

install also cannot handle recursively copying directories. For this, I still prefer mkdir -pv /path/to/dest and cp -afv /sources/source -T /path/to/dest.

Despite these hiccups, however, install is still an incredibly convenient utility for explicit, predictable file installs.

Honorable mentions

While this really wasn't close, there are several other commands I particularly love. Among these are git, curl, fd, and rg.

All of the above are a joy to use, and commonplace in my workflow.