2

I have a one-line script passed into the foreach function in a Makefile, as shown below:

flag:
        $(foreach f, $*.txt, printf "%s\n" 0a "$(grep -o '[0-9]\+' $f | sed 's/.*/read \"&\"/')" "" . w q | ed $f)

What this script line does could be found here. I am just puzzled why it doesn't work this way, because if I put the line into a separate script and call it from the Makefile like this:

flag:
        $(forech f, $*.txt, ./script $f)

it works fine.

I also tried the shell for loop as follows:

flag:
        for f in $*.txt ; do \
          printf "%s\n" 0a "$(grep -o '[0-9]\+' $f | sed 's/.*/read \"&\"/')" "" . w q | ed $f ; \
        done

still no luck. I must touch some subtle points of Makefiles, could anyone enlighten me? Thanks.

Community
  • 1
  • 1
day
  • 2,292
  • 1
  • 20
  • 23

2 Answers2

7

Both too many and not enough $ signs! This lists the *.txt files - note the $$F:

all:
    for F in *.txt ; do \
    echo $$F ; done
  • I tried your way, removing the `$` before `*.txt` and adding `$` before the two occurrences of the variable `f`, but it still doesn't work. – day Jun 05 '11 at 06:01
  • I have solved the problem, thanks for enlightening me, Neil. It is indeed a missing `$` caused the trouble. – day Jun 07 '11 at 18:08
0

The solution is: adding one more $ before the sequence beginning with grep,

flag:
        $(foreach f, $*.txt, printf "%s\n" 0a "$$(grep -o '[0-9]\+' $f | sed 's/.*/read \"&\"/')" "" . w q | ed $f)

or use the old backticks instead

flag:
        $(foreach f, $*.txt, printf "%s\n" 0a "`grep -o '[0-9]\+' $f | sed 's/.*/read \"&\"/'`" "" . w q | ed $f)
day
  • 2,292
  • 1
  • 20
  • 23