Question

I am trying to understand why the script will work with #!/bin/bash but not #!/bin/sh. I am running Cygwin and both sh.exe and bash.exe seem to be identical (same file size).

$ cat 1.sh
#!/bin/sh
while read line; do
  echo ${line:0:9}
done < <(help | head -5)

$ ./1.sh
./1.sh: line 4: syntax error near unexpected token `<'
./1.sh: line 4: `done < <(help | head -5)'

$ cat 2.sh
#!/bin/bash
while read line; do
  echo ${line:0:9}
done < <(help | head -5)

$ ./2.sh
GNU bash,
These she
Type `hel
Use `info
Use `man

Answer 1

Despite being same file, shell analyzes its own name when run and switches to either plain shell or bash mode.