我如何使用Shell脚本原子替换函数

Question

First：in my shell scripts：

[root@localhost ~]# cat  calc.sh 
#! /bin/sh
calc_func()
{

    i=1;
    j=2;
    if [ $i -gt 0 ];then
        return $(($i+$j));
    fi
}   
calc_func  
echo $?

and then， in my text:

[root@localhost ~]# cat calc.txt 
sub_func()
{  

    i=100;
    j=200;
    if [ $i -gt 0 ];then
        return $(($i-$j));
    fi

}

and now, i want to replace the funciton body named calc_func in calc.sh with sub_func's body in calc.txt; let it becomes to this:

[root@localhost ~]# cat  calc.sh 
#! /bin/sh
calc_func()
{

    i=100;
    j=200;
    if [ $i -gt 0 ];then
        return $(($i-$j));
    fi

}   
calc_func  
echo $?

i want to achieve it with shell scripts, how can i fix it ? tips:source or export couldn't be use .

Answer 1

You can do it fairly easily with head , tail , sed and mv . For example:

head -n 2 calc.sh >tmp.sh
sed -n '/{/,/}/p' calc.txt >> tmp.sh
tail -n2 calc.sh >> tmp.sh
mv calc.sh calc.sh.sav; mv tmp.sh calc.sh

You can do that as a one-liner, or as a short script.

Your original calc.sh is now in calc.sh.sav and your new calc.sh with the inner block from calc.txt is in calc.sh , eg

$ cat calc.sh
#! /bin/sh
calc_func()
{

    i=100;
    j=200;
    if [ $i -gt 0 ];then
        return $(($i-$j));
    fi

}
calc_func
echo $?