| 1 | #!/bin/sh
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| 2 |
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| 3 | # bash: descriptors 10 and 255
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| 4 | # osh: 3 and 4 taken: BAD
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| 5 |
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| 6 | # dash: 10 and 11
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| 7 | # mksh: 24 25 26
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| 8 | # zsh: 10 11 12. zsh somehow doesn't run this script correctly. It's not
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| 9 | # POSIX I guess.
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| 10 |
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| 11 | # count FDs greater than 10. 0-9 are reserved for scripts.
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| 12 | count_func() {
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| 13 | local count=0
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| 14 | local reserved=0
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| 15 |
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| 16 | local pid=$$
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| 17 |
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| 18 | # Uncomment this to show the FD table of the pipeline process! The parent
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| 19 | # doesn't change!
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| 20 |
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| 21 | #local pid=$BASHPID
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| 22 |
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| 23 | for path in /proc/$pid/fd/*; do
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| 24 | echo $path
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| 25 | count=$((count + 1))
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| 26 | local fd=$(basename $path)
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| 27 | if test $fd -gt 2 && test $fd -lt 10; then
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| 28 | reserved=$((reserved + 1))
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| 29 | fi
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| 30 | done
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| 31 |
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| 32 | ls -l /proc/$pid/fd
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| 33 |
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| 34 | echo "$count FDs open; $reserved are RESERVED (3-9)"
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| 35 | }
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| 36 |
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| 37 | # What does it look like inside a redirect? _tmp/err.txt must be open.
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| 38 | count_redir() {
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| 39 | {
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| 40 | count_func
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| 41 | } 2> _tmp/err.txt
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| 42 | }
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| 43 |
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| 44 | count_pipeline() {
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| 45 | count_func | cat
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| 46 | }
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| 47 |
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| 48 | # https://stackoverflow.com/questions/2493642/how-does-a-linux-unix-bash-script-know-its-own-pid
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| 49 | pid() {
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| 50 | echo $$ $BASHPID | cat
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| 51 | }
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| 52 |
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| 53 | "$@"
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| 54 |
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