Where is the configuration file?

[nwvh]

No description provided.

[Un1q32]

there is none. pfetch is configured through environment variables. Read the README for more info

[moore-bryan]

sorry for my density, but the README doesn't detail how to set any of those variables and people new to pfetch might need a little more help...

[mag4no10]

You may set environment variables in your .bashrc, .zshrc... to let pfetch know what style of output is the desired, as well as the information that pfetch couldn't gather from your system. An example in your .bashrc :
...
export PF_INFO="ascii title os host kernel uptime pkgs memory shell"
export SHELL="zsh"
...
Check this out for more information README