Here Document

2013年3月20日 星期三 晴

Here Document

1、命令<<标记

输入内容

标记

[root@desktop7 ~]# cat <<EOT

> cengjing

> youyiduan

> zhenshi de gushi

> EOF

> EOT

cengjing

youyiduan

zhenshi de gushi

EOF

[root@desktop7 ~]#

2、统计文件（输入内容）行数

[root@desktop7 ~]# wc -l<<Here

> Hello

> the,wirld

> Wellcome to Chinese

> Here

3

[root@desktop7 ~]#

3、统计

[root@desktop7 ~]# wc -l

jin tian tianqi

hen qing lang

chu chu

hao fengguan

niao er mang feng er ye mang                #只有当Ctrl+d组合键才会终止文件的输入

5

[root@desktop7 ~]#

4、支持变量

[root@desktop7 ~]# A=7758521

[root@desktop7 ~]# cat <<END

> bu yao wen wo wei shen me

> cong qian mei youxun zhao

> girl friend

> yin wei

> wo de jian bang

> hai bu zu yi wei ta zhe feng dang yu

> qi shi wo ye xiang shuo

> $A

> END

bu yao wen wo wei shen me

cong qian mei youxun zhao

girl friend

yin wei

wo de jian bang

hai bu zu yi wei ta zhe feng dang yu

qi shi wo ye xiang shuo

7758521

[root@desktop7 ~]#

5、屏蔽特殊字符

[root@desktop7 ~]# cat <<'END'

> bu yao wen wo wei shen me

> cong qian mei youxun zhao

> girl friend

> yin wei

> wo de jian bang

> hai bu zu yi wei ta zhe feng dang yu

> qi shi wo ye xiang shuo

> $A

> EBD

> END

bu yao wen wo wei shen me

cong qian mei youxun zhao

girl friend

yin wei

wo de jian bang

hai bu zu yi wei ta zhe feng dang yu

qi shi wo ye xiang shuo

$A                                                 #特殊字符$A并未取变量值

EBD

[root@desktop7 ~]#

6、取变量值

[root@desktop7 ~]# m=$(cat <<EOF

> HELLO

> how are you

> fine

> thank you

> and you

> EOF)

[root@desktop7 ~]# echo $m

HELLO how are you fine thank you and you

[root@desktop7 ~]#

7、多行批注

编辑文本中可以用"：<<END"，然后在下面文本中输入“END“，则这之间的内容为多行批注，BASH不会执行。作用等同于加(#)井号，但是许多脚本中并未应用这种方式，仍旧多为井号。