File input in bash script from an array of strings

by

Given an array of strings, I need to input each of these strings as a source file into a build script.

  1. Declare the array (the extra space at the end of the filename is deliberate):
SOURCES=( \
"../../header1.h " \
"../../source1.cpp " \
"../../header2.h " \
"../../header3.h " \
...
"./main.cpp")
  1. Convert contents of array into one string:
SOURCE_AS_STR=""
for val in "${SOURCES[@]}";
do
    SOURCE_AS_STR+=$val
done
  1. Redirect string into a build script:
bash my_build_script.sh < "${SOURCE_AS_STR}"

BASH terminal response: ... No such file or directory

I’ve tried arrays and heredoc strings but I am getting “ambiguous redirect” error as well.

  • Well surely ... shouldn’t be in the array should it?

    – 

  • 2

    Anyway you can use bash my_build_script.sh "${SOURCES[@]}"

    – 




  • If you want the string to go to the stdin of the command, use a “here string”: <<<.

    – 




  • You don’t need those backslash characters in the array declaration. Newlines don’t end a =(...) variable assignment.

    – 




All I needed was to lose the redirect < and I could do bash my_build_script.sh "${SOURCES[@]}" as suggested in comments by Paolo.

My problem was the “redirect was ambiguous”, so I didn’t know I could just drop the < and send the array.

The backslashes (when defining SOURCES) are unnecessary, but they don’t harm.

In your approach, you are telling bash to use the string stored in SOURCE_AS_A_STRING as filename and feed the content of this file into the standard input of the script.

You did not specify, how my_build_script.sh expects the input, so here are various possibilities:

  • If the input is to be processed via stdin, do a

    my_build_script.sh <<<$SOURCE_AS_A_STRING

  • If the input should be passed to the script as a parameter, do a

    my_build_script.sh "$SOURCE_AS_A_STRING"

  • If the input should be passed to the script via the environment (say, via the environment variable BUILD_INPUT), do a

    BUILD_INPUT=$SOURCE_AS_A_STRING my_build_script.sh

Of course the question is why your scripts expects an input (in whatever way) as a single string, and not as list of file names. This smells like a badly designed script file.

Leave a Comment