#cat file1 file2 file3 ...
#cat file.txt
1 2 3
压缩空白行(将文本中多个空白行压缩为单个)
#cat -s file (压缩连续的空白行)
#cat -s file | tr -s '\n' 也可以用tr移除空白行 (将多个空白行压缩为单个)
显示制表符
#cat -T file
输出行号
#cat -n file
1 txt
2 txt
3 txt
在cat << EOF>file.tst与下一个EOF行之间的所有文本都会被当作stdin数据
#!/bin/bash
cat <<EOF>file.txt
this is a test file
this is a test file
this is a test file
EOF
#cat file.txt
this is a test file
this is a test file
this is a test file