Whichls

Whichls refers to a family of Unix-like command-line utilities designed to list and display information about system processes. The primary tool in this family is often named "which" or "whereis," though variations and more specialized tools exist. These commands are fundamental for system administrators and developers seeking to understand the executable paths and locations of installed programs on their operating system.

The "which" command, in its most common form, searches the user's PATH environment variable to locate the full path of an executable file. When a command is typed into the terminal, the shell searches through the directories listed in PATH in sequence until it finds a matching executable. "which" essentially simulates this search process and reports the first match it finds. This is useful for confirming that a command is installed and accessible from the current environment, or for understanding which version of a command will be executed if multiple are present on the system.

A related command, "whereis," goes beyond just executables. It searches for the binary, source, and manual page files for a given command. This provides a more comprehensive view of where all related components of a program are stored on the filesystem. Both "which" and "whereis" are non-interactive and typically return a simple string representing the file path(s) or an indication that the file was not found. Their simplicity makes them efficient tools for quick lookups in command-line operations.