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bashshellloopsevalheredoc

Loop inside "heredoc" in shell scripting


I need to execute series of commands inside an interactive program/utility with parameterized values. Is there a way to loop inside heredoc ? Like below .. Not sure if eval can be of any help here. Below example doesn't seem to work as the interactive doesn't seem to recognize system commands.

#!/bin/sh
list="OBJECT1 OBJECT2 OBJECT3"
utilityExecutable << EOF
for i in $list ; do
utilityCommand $i
done
EOF

Solution

  • Instead of passing a here-document to utilityExecutable, the equivalent is to pipe the required text to it. You can create the desired text using echo statements in a for-loop, and pipe the entire loop output to utilityExecutable:

    #!/bin/sh
    
    list="OBJECT1 OBJECT2 OBJECT3"
    
    for i in $list; do
        echo "utilityCommand $i"
    done | utilityExecutable