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I understand this has been asked before but the answer don't quite give me what I need. I pgrep for a given string which returns a list of PID's containing that string in a variable ($testpid in this case). I then try and split each one of the PID's out, they are sepereated with a space like so:

PIDS:

17717 172132 2138213

Code:

IFS=" " read -a pidarray <<< "$testpid"
echo pidarray[0]

*instead of the echo above i would be assigning each item in the array to its own variable

But I get the following error:

syntax error: redirection unexpected
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    That "redirection unexpected" is what you would get if your shell were not in fact bash. Commented Dec 16, 2014 at 14:13
  • Your question and the title both seem to indicate that your problem was splitting the PIDs into multiple variables, but you've accepted an answer that deals with a different problem. If this is in fact what you wanted, please consider rephrasing the title and question accordingly. Commented Dec 16, 2014 at 14:44
  • @TTT, an excellent point -- I quite glossed over the note that the actual intent was then to assign the array elements to their own variables; there's no need to use an array at all in that case. Answer amended appropriately. Commented Dec 16, 2014 at 15:34
  • @CharlesDuffy Do you think that is, indeed what he meant? I had begun to answer that question, when I saw he marked your original answer as complete. Regardless, your answer solves both now! Commented Dec 16, 2014 at 17:19
  • @TTT, the "instead of the echo above i would be assigning each item in the array to its own variable" makes it fairly clear. Commented Dec 16, 2014 at 18:18

2 Answers 2

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Your syntax was almost correct:

IFS=' ' read -r -a pidarray <<< "$testpid"
echo "${pidarray[0]}"

Note the curly braces needed for the array dereference.

More importantly, check that your shebang is #!/bin/bash, or that you executed your script with bash yourscript, not sh yourscript. The error given is consistent with a shell that doesn't recognize <<< as valid syntax -- which any remotely modern bash always will when invoked as bash; even if /bin/sh points to the same executable, it tells bash to disable many of its extensions from the POSIX spec.

Now, that said -- if your goal is to assign each entry to its own variable, you don't need (and shouldn't use) read -a at all!

Instead:

IFS=' ' read -r first second third rest <<<"$testpid"
printf '%s\n' "First PID is $first" "Second PID is $second"
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4 Comments

Also, /bin/sh doesn't support reading array, only :read [-p prompt] [-r] variable [...]
@jujj, indeed; sh doesn't support arrays at all, but we don't get to that if we're hitting a syntax error before invoking read, so I didn't consider it worth mentioning.
And if you have a variable number of arguments coming in, you can handle them via looping and the eval command, e.g. as for i in {1..3}; eval "var$i=$i"; done. Though, I don't know why you'd want to get away from an array in such an instance, anyway.
@TTT, there are much better ways to do indirect assignments than eval. For instance, printf -v "var$i" %s "$i". See 1.3.3 of mywiki.wooledge.org/BashFAQ/006 for more (and mywiki.wooledge.org/BashFAQ/048 for notes on the eval-considered-harmful premise).
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You can try this one. 

testpid="17717 172132 2138213"
set -- $testpid
echo -e $1 $2

After that use the $1,$2,$3 to get that separately.

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8 Comments

What does that do that set -- $testpid would not, without all the overhead of the subshell?
To be clear -- I think that if modified to fix the inefficiency (and, maybe, with more explicit note of the side effects -- since it does overwrite the argument list) this is a good answer.
...though it also has a problem in the general case of globbing -- the read -r -a approach will put a * into an array element as a literal, whereas this will replace it with a list of filenames in the current directory. Not a problem with PIDs, but maybe a problem elsewhere.
Much better. I still might use -- before the $testpid to prevent arguments that start with dashes from being treated as shell options -- what if $1 were -e? -- but that's a relatively minor quibble. (Similar quibbles apply to quoting expansions on arguments to the echo).
Sorry I missed that one.
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