which
NAME
which - locate a command
SYNOPSIS
which [-a] filename ...
DESCRIPTION
which returns the pathnames of the files (or links) which would be executed in the current environment, had its arguments been given as commands in a
strictly POSIX-conformant shell. It does this by searching the PATH for executable files matching the names of the arguments. It does not follow symbolic links.
whereis
NAME
whereis - locate the binary, source, and manual page files for a command
SYNOPSIS
whereis [-bmsu] [-BMS directory... -f] filename...
DESCRIPTION
whereis locates source/binary and manuals sections for specified files. The supplied names are first stripped of leading pathname components and any (sin‐
gle) trailing extension of the form .ext, for example, .c. Prefixes of s. resulting from use of source code control are also dealt with. whereis then
attempts to locate the desired program in a list of standard Linux places.
OPTIONS
-b Search only for binaries.
-m Search only for manual sections.
-s Search only for sources.
-u Search for unusual entries. A file is said to be unusual if it does not have one entry of each requested type. Thus `whereis -m -u *' asks for
those files in the current directory which have no documentation.
-B Change or otherwise limit the places where whereis searches for binaries.
-M Change or otherwise limit the places where whereis searches for manual sections.
-S Change or otherwise limit the places where whereis searches for sources.
-f Terminate the last directory list and signals the start of file names, and must be used when any of the -B, -M, or -S options are used.
EXAMPLE
Find all files in /usr/bin which are not documented in /usr/man/man1 with source in /usr/src:
example% cd /usr/bin
example% whereis -u -M /usr/man/man1 -S /usr/src -f 16"4
locate
NAME
locate - find files by name
SYNOPSIS
locate [OPTION]... PATTERN...
DESCRIPTION
locate reads one or more databases prepared by updatedb(8) and writes file names matching at least one of the PATTERNs to standard output, one per line.
If --regex is not specified, PATTERNs can contain globbing characters. If any PATTERN contains no globbing characters, locate behaves as if the pattern
were *PATTERN*.
By default, locate does not check whether files found in database still exist. locate can never report files created after the most recent update of the
relevant database.
find
NAME
find - search for files in a directory hierarchy
SYNOPSIS
find [-H] [-L] [-P] [-D debugopts] [-Olevel] [path...] [expression]
DESCRIPTION
This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given file name by evaluating the given expression
from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and opera‐
tions, true for or), at which point find moves on to the next file name.
If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other
users), you should read the "Security Considerations" chapter of the findutils documentation, which is called Finding Files and comes with findutils. That
document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information.