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mapfile bash builtin

This is a discussion on mapfile bash builtin within the Linux Programming forums, part of the Platform Specific Boards category; The bash builtin mapfile reads from standard input and copies lines to the given array (the -t option removes the ...

  1. #1
    - - - - - - - - oogabooga's Avatar
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    mapfile bash builtin

    The bash builtin mapfile reads from standard input and copies lines to the given array (the -t option removes the newline).

    I can't figure out why it works in the first case below but not the second:
    Code:
    $ echo -e "one\ntwo\nthree" > tempfile; mapfile -t an_array1 < tempfile
    $ echo ${an_array1[1]}
    two
    
    
    $ echo -e "one\ntwo\nthree" | mapfile -t an_array2
    $ echo ${an_array2[1]}
             <-- doesn't print anything
    $ echo ${#an_array2[*]}   # print array length
    0
    The cost of software maintenance increases with the square of the programmer's creativity. - Robert D. Bliss

  2. #2
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    bug-bash-gnu - Re: Data piped to 'mapfile', 'readarray', 'read -a' shell builtins is ignored - msg#00087 - OSDir.com
    Looks like it's due to the fact that the pipe operator uses subshells for each of the commands in the pipeline, and those processes don't propagate their shell variables (like an_array2) up to the parent process (the shell that called your piped commands).
    oogabooga likes this.

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