Why is [[ "$input" == name1* || name2* ]] never false?

phigeon 0
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I'm a little befuddled with a script I've been writing - and would appreciate some help! This is one of those cases where each command seems to work fine on their own, but not so when put together into a script. Here's a gist of what I'm trying to do:

input=$1

single_func () {
   command "$input"
}

multi_func () {
   xargs < $input -n 1 single_func
}

if [[ "$input" == name1* || name2* ]];
then
   single_func
elif [[  -f "$input" ]];
then
   multi_func
else
   echo "exiting"
   exit
fi

The idea here is - if the script is invoked with ./script.sh input, if will run if the input starts with name1 or name2, using single_func. If the input provided doesn't start with name1 or name2, and is a file containing a list of items, elif will run (reason for -f) using multi_fuc, which is just single_func running with xarg on the provided file. The 'single_func' component runs on the command line fine on its own (command "input"), and the 'multi_func' component runs fine with a test file (xargs < testfile.txt -n 1 ./single_func.sh). But when I put them together as above and try to run them together, only the first 'if' part works correctly. When provided with a file or some nonsense line not containing name1 or name2, the script simply exits without returning anything. For the curious, I'm running entrez direct commands within the single_func block.
What am I doing wrong?

xargs shell bash if-statement
1 Answers

You need to write:

if [[ "$input" = name1* || "$input" = name2* ]]; then

Otherwise, the right-hand side of your || tests whether name2* is a non-empty string, which it always unconditionally is, making the statement always true.

If you don't want to repeat yourself (and your real use case is complex enough you can't just change it to if [[ "$input" = name[12]* ]]), use a case statement instead:

case $input in
  name1*|name2*)  echo "Either name1 or name2 prefix found";;
  *)              echo "Neither prefix found";;
esac
Charles Duffy0
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