sed work in shell but not script

rbees · 05-10-2015, 08:32 PM

Ladies & Gents

It seams that I am unable to figure this out at this time. I do remember reading about a similar thing at one point over on stack exchange or somewhere but can't find it at the moment.

What I am trying to do is change a number (100 through 150) say 101 to a1 to be used as part of a file name.

Code:

count=101
elif ((count > 99))&&((count < 110));then
 echo $count | sed '/^10/a/'> $chapter
 echo $chapter

results in the following when executed

Code:

+ echo 101
+ sed '/^10/a/'
+ echo 71

I have tried several iterations of the above sed command with no joy.

In another place where I have a very similar sed, except with a "d" instead of an "a" I get a different error

Code:

+ echo 131
+ sed '/^13/d/'
sed: -e expression #1, char 7: extra characters after command
+ echo 71

The relevant code

Code:

count=$1
for (( a = 1; a < 6; a++)); do
  local chapter
  
  if ((count < 100)); then
    chapter=$count
    echo $chapter
  elif ((count > 99))&&((count < 110));then
    echo $count | sed '/^10/a/'> $chapter
    echo $chapter
  elif ((count > 109))&&((count < 120));then
    echo $count | sed '/^11/b/' > $chapter
    echo $chapter
  elif ((count > 119))&&((count < 130));then
    echo $count | sed '/^12/c/' > $chapter
    echo $chapter
  elif ((count > 129))&&((count < 140));then
    echo $count | sed '/^13/d/' > $chapter
    echo $chapter
  elif ((count > 139))&&((count < 150));then
    echo $count | sed '/^14/e/' > $chapter
    echo $chapter
  else
    chapter="f0"
  fi
count=$((count + 30))

done

It seams to exhibit this behavior every time it tries to make the change. If I had more time to play I might be able to figure it out by myself but play times is very limited due to my work load.

Thanks for any pointers.

syg00 · 05-10-2015, 08:47 PM

Perhaps you should be using the substitute command ? As in

Code:

sed 's/^10/a/'

NevemTeve · 05-10-2015, 10:20 PM

Code:

echo ... > $chapter

what does this do?

I would use this:

Code:

chapter=$(echo ...)

ondoho · 05-11-2015, 02:59 PM

Quote:

Originally Posted by NevemTeve

I would use this:

Code:

chapter=$(echo ...)

no, i would use:

Code:

chapter="..."

rbees · 05-11-2015, 05:29 PM

Thanks guys,

Using a combination of the suggestions you posted got me past it. I added the 's/ back in as sgv00 suggested and that got me part way, but as I was thinking about it today while on the road what NevemTeve suggested made sense. So I did that too. And we have joy

I looked at ondoho's suggestion and would like to understand it better. I think it has something to do with shell expansion, but the only info I have at this point is
https://github.com/koalaman/shellcheck/wiki/SC2001

That explanation indicates that it will not work very well for complex changes. Is mine to complex? With needing to replace the first 2 digits of the number with a letter.

Anyway thanks

ondoho · 05-12-2015, 11:59 AM

Quote:

Originally Posted by rbees

I looked at ondoho's suggestion and would like to understand it better.

i took nevemteve's reply literally. obviously the 3 dots are supposed to stand for sth else.
my reply was a little flippant.
applied to the above code example, nevemteve's answer is correct, and not mine.

upon deeper examination, i'm not sure if you can "echo ... > $var" at all.
i would think ">" would write into a file by the name of whatever $var is set to.

edit: btw, the following two lines do the same:

Code:

chapter=$(echo $count | sed 's/^10/a/')
chapter=${count/#10/a}

see here.

rbees · 05-12-2015, 12:35 PM

Thanks

Quote:

the following two lines do the same:
Code:
chapter=$(echo $count | sed 's/^10/a/')
chapter=${count/#10/a}

does the second need the # wouldn't chapter=${count/10/a} don the same thing?

ondoho · 05-14-2015, 06:06 AM

Quote:

Originally Posted by rbees

does the second need the # wouldn't chapter=${count/10/a} don the same thing?

depends on what you want.
please read the link i provided.

edit: actually, no. "#" is equivalent to "^" in this example.