Download page
https://blast.ncbi.nlm.nih.gov/Blast.cgi?CMD=Web&PAGE_TYPE=BlastDocs&DOC_TYPE=Download
Ubuntu / Debian
sudo apt-get install ncbi-blast+
CentOS
# download latest BLAST version
wget ftp://ftp.ncbi.nlm.nih.gov/blast/executables/blast+/LATEST/ncbi-blast-2.8.1+-x64-linux.tar.gz
# decompress
tar -zxvf ncbi-blast-2.8.1+-x64-linux.tar.gz
# add BLAST location to system PATH
export PATH=$HOME/tools/BLAST/ncbi-blast-2.8.1+/bin:$PATH