List all packages that depend on a certain package with pacman

To list the dependencies use pacman -Si or pacman -Qi

To list the reverse dependencies : pacman -Sii

Arch-linux: Querying package dependencies

How can I list all installed packages that are depending on a certain other package

For one level dependency use pacman -Qi package_name | grep 'Depends On'

e.g:

$ pacman -Qi jack | grep 'Depends On'
Depends On      : alsa-lib  db  glibc  gcc-libs  libsamplerate  libzita-alsa-pcmi.so=0-64  libzita-resampler.so=1-64

To view the dependency tree of a package use pactree which is owned by pacman-contrib

e.g:

$ pactree jack
jack
├─alsa-lib
│ ├─glibc
│ │ ├─linux-api-headers provides linux-api-headers>=4.10
│ │ ├─tzdata
│ │ └─filesystem
│ │   └─iana-etc
│ ├─alsa-topology-conf
│ └─alsa-ucm-conf
├─db
│ ├─gcc-libs
│ │ └─glibc provides glibc>=2.27
│ └─bash provides sh
│   ├─readline provides readline>=7.0
│   │ ├─glibc
│   │ ├─ncurses
│   │ │ ├─glibc
│   │ │ └─gcc-libs
│   │ └─ncurses provides libncursesw.so=6-64
│   ├─glibc
│   └─ncurses
├─glibc
├─gcc-libs
├─libsamplerate
│ └─glibc
├─zita-alsa-pcmi provides libzita-alsa-pcmi.so=0-64
│ ├─alsa-lib
│ ├─gcc-libs
│ └─glibc
└─zita-resampler provides libzita-resampler.so=1-64
  ├─gcc-libs
  └─glibc

To view the dependent tree of a package, pass the reverse flag -r to pactree