  Let $\mathcal{F}$ be a family of $3$-uniform linear hypergraphs. The linear
Tur\'an number of $\mathcal F$ is the maximum possible number of edges in a
$3$-uniform linear hypergraph on $n$ vertices which contains no member of
$\mathcal{F}$ as a subhypergraph.
  In this paper we show that the linear Tur\'an number of the five cycle $C_5$
(in the Berge sense) is $\frac{1}{3 \sqrt3}n^{3/2}$ asymptotically. We also
show that the linear Tur\'an number of the four cycle $C_4$ and $\{C_3, C_4\}$
are equal asmptotically, which is a strengthening of a theorem of Lazebnik and
Verstra\"ete.
  We establish a connection between the linear Tur\'an number of the linear
cycle of length $2k+1$ and the extremal number of edges in a graph of girth
more than $2k-2$. Combining our result and a theorem of Collier-Cartaino,
Graber and Jiang, we obtain that the linear Tur\'an number of the linear cycle
of length $2k+1$ is $\Theta(n^{1+\frac{1}{k}})$ for $k = 2, 3, 4, 6$.
