统计染色体的核苷酸个数，GC含量

#统计所有染色的长度
samtools faidx Pisum_sativum_v1a.fa

#分染色体统计序列AGCTN含量，GC%，需要先对fa文件进行分割
grep -v '>' chr1.fa| perl -ne  '{$count_A=$count_A+($_=~tr/A//);$count_T=$count_T+($_=~tr/T//);$count_G=$count_G+($_=~tr/G//);$count_C=$count_C+($_=~tr/C//);$count_N=$count_N+($_=~tr/N//)};END{print qq{total count,A,G,C,T,N,is },$count_A+$count_T+$count_G+$count_C+$count_N,qq{\t},$count_A,qq{\t},$count_G,qq{\t},$count_C,qq{\t},$count_T,qq{\t},$count_N, qq{\nGC%:},($count_G+$count_C)/($count_A+$count_T+$count_G+$count_C+$cont_N),qq{\n}}'