useradd bash标准语法错误

Question

store=$(cat /etc/passwd | grep ^$outName | awk '{print 1}' | cut -b4- | sort -n)
    #echo $store
    num=$(echo $store + 1 | bc ) 

(standard_in) 1: syntax error useradd: user 'cjh' already exists (standard_in) 1: syntax error useradd: user 'txj' already exists (standard_in) 1: syntax error useradd: user 'rbh' already exists (standard_in) 1: syntax error useradd: user 'cjh' already exists

我错过的错误在哪里？我想将用户名从cjh1（如果已存在）增加到cjh2...