Hydrolysis of nitriles: Amide vs Carboxylic acid
Hydrolysis of nitrile is pH dependent. It will lead to formation of different products based on pH.
Theoretically, nitrile hydrolyze to form amide and then ammonium salt.
$$\ce{RCN -&gt;[H2O] RCONH2 -&gt;[H2O] RCOONH4}$$
But in practice, the reaction between nitriles and water is so slow that it is considered negligible. The nitrile is instead heated with either a dilute acid such as dilute hydrochloric acid, or with an alkali such as sodium hydroxide solution to accelerate the hydrolysis reaction. But this pH dependent reaction yields different products.

Acid hydrolysis: yields carboxylic acid

$$\ce{RCN + 2H2O + HCl -&gt; RCOOH + NH4Cl}$$

Alkaline hydrolysis: yields sodium carboxylate salt

$$\ce{RCN + H2O + NaOH-&gt; RCOONa + NH3}$$
To obtain amide, hydrolysis is done selectively and in controlled manner. It can be done in both acidic and alkaline medium. In acidic medium, nitriles are converted into amide in a single step process using TFA-$\ce{H2SO4}$ mixture as reagent.

In alkaline medium, it can done using alkaline solution of hydrogen peroxide (see @Light Yagami's answer).
Reference

Chemguide
Facile and Highly Selective Conversion of Nitriles to Amides via Indirect Acid-Catalyzed Hydration Using TFA or AcOH−H2SO4, Jarugu Narasimha Moorthy and Nidhi Singhal, The Journal of Organic Chemistry 2005 70 (5), 1926-1929
DOI: 10.1021/jo048240a