egrep "12" 1.txt == grep -E "12" 1.txt
fgrep "23" 1.txt == grep -F "12" 1.txt
tee 3.txt //读取标准输入，输出成文件
cmp 1.txt 2.txt
cut -c1-1 1.txt 显示每列的第几到第几的字符
