Some programs needs their files to be seekable, for example objdump does.

$ objdump -D -b binary -m i8086 <(echo 0xea 0x5b 0xe0 0x00 0xf0|xxd -r -p)
objdump: Warning: '/proc/self/fd/11' is not an ordinary file

It would be convenient to have process substitution use temporary files.

I can see in the man page that bash can fallback to temporary files with process substitution, but can I explicitly ask him to use temporary files?

Like zsh's =().

$ objdump -D -b binary -m i8086 =(echo 0xea 0x5b 0xe0 0x00 0xf0|xxd -r -p)

/tmp/zsh1u1Nrw:     file format binary

Disassembly of section .data:

00000000 <.data>:
   0:   ea 5b e0 00 f0          ljmp   $0xf000,$0xe05b
  • I doubt it, but you can always use mktemp. – Wildcard Mar 14 '16 at 7:48
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    Maybe you should try compile bash with HAVE_DEV_FD set to 0. – cuonglm Mar 14 '16 at 7:54
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    You could use a seekable here string instead: objdump -D -b binary -m i8086 /dev/stdin <<<$(echo 0xea 0x5b 0xe0 0x00 0xf0|xxd -r -p) – meuh Mar 14 '16 at 8:40
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    Oops. The here string version silently drops the null char! – meuh Mar 14 '16 at 13:32
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    @Wildcard using fifo is not possible with objdump, that's the whole point of the question. Otherwise <() was good enough. – Elazar Leibovich Mar 14 '16 at 21:40

Based on meuh's comment; apparently bash here-strings can be abused as temporary files, try this:

( echo 0xea 0x5b 0xe0 0x00 0xf0 | 
  xxd -r -p >/dev/fd/9; objdump -D -b binary -m i8086 /dev/fd/9) 9<<<''
  • The trick is that here documents and here strings use temporary files under the hood (replace objdump ... with stat /dev/fd/9 to see, it won't be a problematic FIFO or a pipe, but a symlink to a file in /tmp or $TMPDIR). – mr.spuratic Sep 21 '16 at 10:43
  • I used your answer's method for my objdump situation. Interestingly, it only worked for me with gcc -o /dev/fd/9 [ . . . ], not with gcc >&9 -o - [ . . . ]. I was going to write an answer (not to the objdump situation, but for a non-null-sensitive situation) that used a here document with a command substitution, but then I saw that you had already mentioned a here string in the question comments, which is even better. – clacke Oct 4 '16 at 9:41

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