search for either "matrix" or "array"

class matrix

search for files containing both "class" and "matrix"

class Matrix

search for files containing both "class" (case insensitive) and "Matrix" (case sensitive)

class Matrix case:yes

search for files containing "class" and "Matrix", both case sensitively

"class Matrix"

search for files with the phrase "class Matrix"

DNAString -RNAString

search for files with the word "DNAString" but not the word "RNAString"

matrix file:Rd

search for the word "matrix" in files whose name contains "Rd"

matrix file:(R|r)$

search for the word "matrix" in files whose name ends with either "R" or "r"

SparseMatrix lang:c

search for "SparseMatrix" in C source code

f:\.R$

search for files whose name ends with ".R"

path -file:Rd

search for the word "path" excluding files whose name contains "Rd"

foo.*bar

search for the regular expression "foo.*bar"

-(Path File) Stream

search "Stream", but exclude files containing both "Path" and "File"

-Path\ file Stream

search "Stream", but exclude files containing "Path File"

close r:hdf5

search for "close" in repositories whose name contains "hdf5"

To list packages, try:

r:seq

list packages whose name contains "seq".

r:Seq

Reposity search is case sensitive. List packages whose name contains "Seq".

r:Seq ‑r:RNA

list packages whose name contains "Seq" but not "RNA".