| 1 |
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| 2 | #### Process sub input
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| 3 | f=_tmp/process-sub.txt
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| 4 | { echo 1; echo 2; echo 3; } > $f
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| 5 | cat <(head -n 2 $f) <(tail -n 2 $f)
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| 6 | ## STDOUT:
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| 7 | 1
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| 8 | 2
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| 9 | 2
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| 10 | 3
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| 11 | ## END
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| 12 |
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| 13 | #### Process sub from external process to stdin
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| 14 | seq 3 > >(tac)
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| 15 | ## STDOUT:
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| 16 | 3
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| 17 | 2
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| 18 | 1
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| 19 | ## END
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| 20 |
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| 21 | #### Process sub from shell to stdin
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| 22 | { echo 1; echo 2; echo 3; } > >(tac)
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| 23 | ## STDOUT:
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| 24 | 3
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| 25 | 2
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| 26 | 1
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| 27 | ## END
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| 28 |
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| 29 | #### Non-linear pipeline with >()
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| 30 | stdout_stderr() {
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| 31 | echo o1
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| 32 | echo o2
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| 33 |
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| 34 | sleep 0.1 # Does not change order
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| 35 |
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| 36 | { echo e1;
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| 37 | echo warning: e2
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| 38 | echo e3;
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| 39 | } >& 2
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| 40 | }
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| 41 | stdout_stderr 2> >(grep warning) | tac >$TMP/out.txt
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| 42 | wait $! # this does nothing in bash 4.3, but probably does in bash 4.4.
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| 43 | echo OUT
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| 44 | cat $TMP/out.txt
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| 45 | # PROBLEM -- OUT comes first, and then 'warning: e2', and then 'o2 o1'. It
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| 46 | # looks like it's because nobody waits for the proc sub.
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| 47 | # http://lists.gnu.org/archive/html/help-bash/2017-06/msg00018.html
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| 48 | ## STDOUT:
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| 49 | OUT
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| 50 | warning: e2
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| 51 | o2
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| 52 | o1
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| 53 | ## END
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| 54 |
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| 55 | #### $(<file) idiom with process sub
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| 56 | echo FOO >foo
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| 57 |
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| 58 | # works in bash and zsh
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| 59 | echo $(<foo)
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| 60 |
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| 61 | # this works in zsh, but not in bash
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| 62 | tr A-Z a-z < <(<foo)
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| 63 |
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| 64 | cat < <(<foo; echo hi)
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| 65 |
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| 66 | ## STDOUT:
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| 67 | FOO
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| 68 | hi
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| 69 | ## END
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| 70 | ## OK zsh STDOUT:
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| 71 | FOO
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| 72 | foo
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| 73 | FOO
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| 74 | hi
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| 75 | ## END
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| 76 |
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| 77 | #### status code is available
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| 78 |
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| 79 | shopt --set parse_at
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| 80 |
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| 81 | cat <(seq 2; exit 2) <(seq 3; exit 3)
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| 82 |
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| 83 | case $SH in bash|zsh) exit ;; esac
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| 84 |
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| 85 | echo status @_process_sub_status
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| 86 | echo done
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| 87 |
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| 88 | ## STDOUT:
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| 89 | 1
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| 90 | 2
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| 91 | 1
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| 92 | 2
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| 93 | 3
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| 94 | status 2 3
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| 95 | done
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| 96 | ## END
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| 97 | ## N-I bash/zsh STDOUT:
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| 98 | 1
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| 99 | 2
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| 100 | 1
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| 101 | 2
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| 102 | 3
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| 103 | ## END
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| 104 |
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| 105 | #### shopt -s process_sub_fail
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| 106 |
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| 107 | case $SH in bash|zsh) exit ;; esac
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| 108 |
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| 109 | shopt --set parse_at
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| 110 |
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| 111 | cat <(echo a; exit 2) <(echo b; exit 3)
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| 112 | echo status=$? ps @_process_sub_status
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| 113 |
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| 114 | echo __
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| 115 | shopt -s process_sub_fail
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| 116 |
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| 117 | cat <(echo a; exit 2) <(echo b; exit 3)
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| 118 | echo status=$? ps @_process_sub_status
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| 119 |
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| 120 | # Now exit because of it
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| 121 | set -o errexit
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| 122 |
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| 123 | cat <(echo a; exit 2) <(echo b; exit 3)
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| 124 | echo status=$? ps @_process_sub_status
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| 125 |
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| 126 | ## status: 3
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| 127 | ## STDOUT:
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| 128 | a
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| 129 | b
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| 130 | status=0 ps 2 3
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| 131 | __
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| 132 | a
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| 133 | b
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| 134 | status=3 ps 2 3
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| 135 | a
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| 136 | b
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| 137 | ## END
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| 138 | ## N-I bash/zsh status: 0
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| 139 | ## N-I bash/zsh STDOUT:
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| 140 | ## END
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| 141 |
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| 142 | #### process subs and pipelines together
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| 143 |
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| 144 | # zsh is very similar to bash, but don't bother with the assertions
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| 145 | case $SH in bash|zsh) exit ;; esac
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| 146 |
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| 147 | shopt --set parse_at
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| 148 |
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| 149 | f() {
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| 150 | cat <(seq 1; exit 1) | {
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| 151 | cat <(seq 2; exit 2) <(seq 3; exit 3)
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| 152 |
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| 153 | # 2022-11 workaround for race condition: sometimes we get pipeline=141 4
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| 154 | # instead of pipeline=0 4, which means that the first 'cat' got SIGPIPE.
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| 155 | # If we make this part of the pipeline take longer, then 'cat' should have
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| 156 | # a chance to finish.
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| 157 |
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| 158 | sleep 0.01
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| 159 |
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| 160 | (exit 4)
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| 161 | }
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| 162 | echo status=$?
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| 163 | echo process_sub @_process_sub_status
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| 164 | echo pipeline @_pipeline_status
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| 165 | echo __
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| 166 | }
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| 167 |
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| 168 | f
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| 169 |
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| 170 | ## STDOUT:
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| 171 | 1
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| 172 | 2
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| 173 | 1
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| 174 | 2
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| 175 | 3
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| 176 | status=4
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| 177 | process_sub 2 3
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| 178 | pipeline 0 4
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| 179 | __
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| 180 | ## END
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| 181 | ## N-I bash/zsh STDOUT:
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| 182 | ## END
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| 183 |
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| 184 | #### process sub in background &
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| 185 |
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| 186 | cat <(seq 3; sleep 0.1) & wait
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| 187 |
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| 188 | echo sync
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| 189 |
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| 190 | # This one escapes, and the shell should still exit
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| 191 | cat <(sleep 0.1) &
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| 192 |
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| 193 | echo fork
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| 194 |
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| 195 | ## STDOUT:
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| 196 | 1
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| 197 | 2
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| 198 | 3
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| 199 | sync
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| 200 | fork
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| 201 | ## END
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