[bash] Executing script that is held in a variable Post: 302387562

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Top Forums Shell Programming and Scripting [bash] Executing script that is held in a variable Post 302387562 by Scrutinizer on Sunday 17th of January 2010 08:42:34 AM

01-17-2010

Moderator

Maybe we are making this too complicated. If I have an input file like so:

Code:

# cat infile
This is line 1
This is line 2
This is line 3
This is line 4
This is line 5
[script-nameofscript]
#!/usr/bin/perl -w
use strict;
print "Hello, Perl!\n";
[/script-nameofscript]
This is line 10
This is line 11
This is line 12
This is line 13
This is line 14

And if I use a script like this:

Code:

#!/bin/bash
script=""
shebang=""
reading_script=0
while IFS= read -r line
do
  if [[ $reading_script -eq 1 ]]; then
    if [[ $line == "[/script-"* ]]; then
      reading_script=0
      eval "${shebang#\#!}" <(printf "$script")
      script=""
      shebang=""
    else
      script="$script$line"
    fi
  else
    if [[ $line == "[script-"* ]]; then
      reading_script=1
      IFS= read -r shebang
    else
      printf "$line\n"
    fi
  fi
done < infile

Then the output is:

Code:

This is line 1
This is line 2
This is line 3
This is line 4
This is line 5
Hello, Perl!
This is line 10
This is line 11
This is line 12
This is line 13
This is line 14

Or is that not what you had in mind?

---------- Post updated at 14:39 ---------- Previous update was at 14:16 ----------

Slightly optimized script:

Code:

#!/bin/bash
reading_script=false
while IFS= read -r line
do
  case $line in
    "[/script-"*)
       reading_script=false
       eval "${shebang#\#!}" <<< $script
       script=""; shebang="" ;;
    "[script-"*)
       reading_script=true
       IFS= read -r shebang ;;
    *)
       if $reading_script; then
         script="$script$line"
       else
         printf "$line\n"
       fi ;;
  esac
done < infile

---------- Post updated at 14:42 ---------- Previous update was at 14:39 ----------

Posix compliant version:

Code:

#!/bin/sh
reading_script=false
while IFS= read -r line
do
  case $line in
    "[/script-"*)
       reading_script=false
       printf "$script" | eval "${shebang#\#!}"
       script=""; shebang="" ;;
    "[script-"*)
       reading_script=true
       IFS= read -r shebang ;;
    *)
       if $reading_script; then
         script="$script$line"
       else
         printf "$line\n"
       fi ;;
  esac
done < infile

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