2

I need to pass a variable to a Perl statement from a bash script through sqlplus, to edit a file. It works fine without passing the count variable but encounters a problem when passing it.

count=$( sqlplus -s test/test <<-EOF
    set pagesize 0;
    set feedback off;
    set verify off;
    set heading off echo off;
        select count(*) from test;
    exit;
EOF)

if [ "$count" != "" ] && [ $count != "0" ]; then

    perl -lpe 'print "Total Number of Rejected Files = "$count"" if $. == 10' Results.txt >> data.txt

else

fi

As far as I know, my problem only with this part "$count". I have tried a lot of things like :

perl -lpe 'print "Total Number of Rejected Files = $ENV{'count'}" if $. == 10' Results.txt >> data.txt

and this :

perl -lpe 'print "Total Number of Rejected Files = $ENV{count}" if $. == 10' Results.txt >> data.txt

but the problem is that the bash variable does not expand through the perl statement.

Improve this question
1
  • 1
    Your perl code is expecting to process Results.txt but you don't seem to declare or use that anywhere Commented Apr 20, 2020 at 12:06

1 Answer 1

Reset to default
6

Your $ENV approach will work just fine, you just need to export the shell variable first. Your perl script is running in a subshell, so the only way it will see the variable is if you export it first:

count=$( sqlplus -s test/test <<-EOF
    set pagesize 0;
    set feedback off;
    set verify off;
    set heading off echo off;
        select count(*) from test;
    exit;
EOF)

export count

if [ "$count" != "" ] && [ $count != "0" ]; then
    perl -lpe 'print "Total Number of Rejected Files = $ENV{count}" if $. == 10' Results.txt >> data.txt
fi

I am a bit confused about your perl command though. perl -lpe '' Results.txt means "print each line of Results.txt after applying the script given by -e to it. But you aren't actually doing anything to Results.txt, so what's the point?

Your code will simply print out every line of Results.txt and then, on the 10th line, it will also print Total Number of Rejected Files = and the value of $count. If that's really what you want to do, then great. It just seems very unlikely that you would in fact want this.

Improve this answer
5
  • I am not familiar with perl: how do hard quotes not suppress (shell) variable expansion here? Am I mixing things up? Commented Apr 20, 2020 at 12:11
  • 3
    @Fiximan essentially, yes. Perl is a programming language, not a shell tool, so the internal $ are its own variables. Here, by exporting the shell variable, we make it available to the Perl environment which can see all shell environment variables in the hash %ENV. Commented Apr 20, 2020 at 12:13
  • So $ENV{var} draws the var form the environment - makes sense like this. Thanks. Commented Apr 20, 2020 at 12:16
  • @terdon it Inserts a new line at specific line number, here im just trying to insert a new line at line 10 , also it acts like positional command arguments: perl -lpe 'BEGIN{$n=shift; $s=shift}; print $s if $. == $n' 10 "Total Number of Rejected Files = $ENV{count}" file, your solution above works fine but the problem output looks like: Total Number of Rejected Files = 1thers several tabs between = and 1how can i avoid these spaces? Commented Apr 20, 2020 at 12:32
  • 1
    @NikolanAsad I'm sorry but I don't understand what you mean. Yes, your command will print out Total Number... at line 10. If that is what you want, then great. It just seems like an odd requirement. There is nothing here that would insert tabs, if you see tabs, then they were already there in your input. Most probably in the $count variable. Also, your shift commands won't do anything, your @ARGV array is empty. Commented Apr 20, 2020 at 13:32

You must log in to answer this question.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.