How to parse the variable in .mk file?

Shell Programming and Scripting
1

Hi all,
I am passing a variable in .mk file as

NEED="TEST=Name WORK=Ps DEL=let"

I need to echo and export each variable like TEST, WORK. DEL

TEST=Name 
WORK=Ps 
DEL=let

We have to parse the NEED variable which may contain many elements like TEST, DEL& etc..

Any idea on this please. I am using Ubuntu

--Regards,
ricky

2

If:
1) your input is guaranteed to be properly delimited by single blanks always,

2) the item=value pairs will contain no further spaces

then the following may work, provided that you use a common shell (and not Ubuntus standard shell dash ). Notice that you may need to add additional tests, trims and other measures to this skeleton because real-world input might not be as well-behaved as is ideal:

input="$1"
buf=""

while [ -n "$input" ] ; do
     buf="${input##* }"               # these two lines chop off 
     input="${input% ${buf}}"         # one item=value pair after the other

     echo "$buf"
     eval export "$buf"
done

Note also that the input string is tokenized backwards, so that the input a=b c=d e=f will result in:

export e=f
export c=d
export a=b

in this order.

I hope this helps.

bakunin

3

Hi,
When I implemented this on my Makefile, I got errors

while [ -n "nput" ] ; do
/bin/bash: -c: line 1: syntax error: unexpected end of file

code:

	
input=NEED="TEST=Name WORK=Ps DEL=let"
all:
                while [ -n "$(input)" ] ; do
		buf="${input##* }"               # these two lines chop off 
		input="${input% ${buf}}"         # one item=value pair after the other
		echo "$buf"
		eval export "$buf"
	done

Do you have any idea on this and changes needed to get the output as needed please.

4

yes, and this probably gives a hint:

Notice that "$input" is not "$input" any more but "nput". I suppose half of the code (which is basically all variable expansion) is interpreted away by the make -utility itself. Also notice that make will call every command in a separate shell, therefore multi-line commands/scripts like the one i gave you will not work this way, because they need to maintain context from one line to the next.

Put the code into a script file and call that instead of directly including it into a make-rule. Furthermore, this:

looks different than what you gave as example input and will fail with the code i wrote anyway. Have you read the caveats i included in my first answer?

I hope this helps.

bakunin

5

Thanks Bakunin,
But When I tried your code in the script its not stopping. It keeps on printing TEST=Name infinitely. Could you give some correction on this, please

6

That is - as i have said already - because the format of your input string is not in the same format as in your post #1. This:

input=NEED="TEST=Name WORK=Ps DEL=let"

does not make any sense syntactically and it is not of the form item1=value1 item2=value2 item3=value3 ... which would be necessary for my algorithm to work - as i have already stated in my first answer!

Give me a REAL EXAMPLE OF WHAT YOU WANT TO PROCESS and i will give you a real solution, because what you have shown me is not only different than what you first asked to process, it will also generate a syntax error if you, to quote yourself:

because

input=NEED="TEST=Na...

is not a syntactically correct shell statement. Otherwise, tell me what the expected outcome should be. Show me the statement my script should produce from this input.

bakunin

7

Hi,
I am really sorry for the confusions, I tried like this way

hacker@hacker:~$ cat test.sh 
#!/bin/bash

NEED="TEST=Name WORK=Ps DEL=let"
buf=""

while [ -n "$NEED" ] ; do
     buf="${NEED##* }"               # these two lines chop off 
     NEED="${NEED% ${buf}}"         # one item=value pair after the other

     echo "$buf"
     eval export "$buf"
done

where I got my output as
TEST=Name
TEST=Name
TEST=Name
TEST=Name
``
``.
``
The output is not ending,
My Real Need:
where I have declared the variable in my MAKEFILE

NEED="TEST=Name WORK=Ps DEL=let"

with the same format with single space delimiting but it not just only three, it can be 'n' number.
Now I need to parse each item with its value and export them for further usage in the same MAKEFILE , as you said a=b, c=d , e=f , g=h etc..

Like say, I have done parsing

TEST=Name
WORK=Ps
DEL=let

In the same MAKEFILE, I have to make use of this WORK, where

echo $(WORK) 
Ps

should print. I hope I cleared the context of my need.
Any help please, I am rolling my head to get this done.

Regards,
ricky

8

How about:

NEED="TEST=Name WORK=Ps DEL=let"


for X in $NEED
do
       echo $X
done
9

Thanks Corona,
I suppose to export those parsed individual variables and use them in the MAKEFILE. Like

echo $WORK 
Ps

echo $TEST
Name 

echo $DEL
let

Any inputs please,
I tried adding

  eval export "$X"

but I can't see in printenv

---------- Post updated at 08:07 PM ---------- Previous update was at 11:16 AM ----------

Any suggestions please,
I tried the way of using sed

	sed 's/ /\n/g' <<< $NEED

which gives output as
TEST=Name
WORK=Ps
DEL=let

but, I can't export the values, any idea to export the values in Makefile

10

Isn't that from your makefile? Why not just set the variables you want to set?

11

"Any inputs please" and / or "Any suggestions please" are not too popular demands in these forums, esp. if repeated several times. If people know or find an answer to - esp. somewhat unclear like your - requests, they will come up with it now or sometime - I don't think urging them like above will make them post sth. head over heels.
If I only knew what the meaning of "export the values in Makefile" were, I might come up with a proposal. To me, a makefile is just textual data, a prescription of conditions and dependencies to be read and executed by the make tool. IF a variable is referenced in a makefile , and IF that variable has been exported in the parent shell, THEN make will be able to process the expanded value of the variable.