1 | #!/usr/bin/env bash
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2 | #
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3 | # test/process-table-portable.sh: helper for process-table.sh.
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4 | #
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5 | # This is a portable shell script, since it has to run under dash, mksh, etc.
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6 | #
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7 | # Usage:
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8 | # test/process-table-portable.sh <function name>
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9 |
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10 | setup() {
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11 | mkdir -p _tmp
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12 | ln -s -f -v $(which cat) _tmp/cat2
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13 | }
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14 |
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15 | readonly PS_COLS='pid,ppid,pgid,sid,tpgid,comm'
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16 |
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17 | show_process_table() {
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18 | # by default, it shows processes that use the same terminal
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19 | #ps -o pid,ppid,pgid,sid,tname,comm | cat | _tmp/cat2
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20 |
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21 | # - bash is the parent of ps, cat, ca2
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22 | # - the PGID is the same as bash? Oh this is for a NON-INTERACTIVE SHELL.
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23 | # - TPGID: controlling terminal's notion of foreground pgid?
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24 | # - it's always the same number, so it's misleading to associate with a process
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25 | # - see APUE section on setpgid(), tcsetgprp()
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26 |
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27 | local sh=$1
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28 | local snippet=$2
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29 |
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30 | case $snippet in
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31 | fgproc)
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32 | echo '[foreground process]'
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33 | ps -o $PS_COLS
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34 | ;;
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35 | bgproc)
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36 | echo '[background process]'
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37 | ps -o $PS_COLS &
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38 | wait
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39 | ;;
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40 |
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41 | # - Gets its own PGID
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42 | # - Hm UNLIKE bgpipe it also gets its own TPGID? Seems consistent in all
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43 | # shells. Why is that?
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44 | fgpipe)
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45 | echo '[foreground pipeline, last is external]'
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46 | ps -o $PS_COLS | cat | _tmp/cat2
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47 | ;;
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48 |
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49 | fgpipe-lastpipe)
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50 | echo '[foreground pipeline, last is builtin]'
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51 | ps -o $PS_COLS | _tmp/cat2 | while read -r line; do echo "$line"; done
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52 | ;;
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53 |
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54 | bgpipe)
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55 | # For interactive shells, the TPGID is different here.
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56 | # Foreground: it matches the PGID of 'ps | cat | cat2'
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57 | # Background: it matches the PGID of bash!
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58 |
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59 | echo '[background pipeline]'
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60 | ps -o $PS_COLS | cat | _tmp/cat2 &
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61 | wait
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62 | ;;
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63 |
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64 | bgpipe-lastpipe)
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65 | echo '[background pipeline, last is builtin]'
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66 | ps -o $PS_COLS | _tmp/cat2 | while read -r line; do echo "$line"; done &
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67 | wait
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68 | ;;
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69 |
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70 | subshell)
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71 | # does NOT create a new process group. So what happens when it's
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72 | # interrupted?
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73 |
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74 | echo '[subshell]'
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75 | ( ps -o $PS_COLS; echo ALIVE )
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76 | # subshell gets its own PGID in every shell!
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77 | ;;
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78 |
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79 | csub)
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80 | # does NOT create a new process group. So what happens when it's
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81 | # interrupted?
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82 | echo '[command sub]'
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83 | local x
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84 | x=$(ps -o $PS_COLS)
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85 | echo "$x"
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86 | ;;
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87 |
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88 | psub)
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89 | case $sh in (dash|mksh)
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90 | return
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91 | esac
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92 |
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93 | echo '[process sub]'
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94 | # use 'eval' as workaround for syntax error in dash and mksh
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95 | eval "cat <(ps -o $PS_COLS)"
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96 | # RESULTS
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97 | # zsh: ps and cat are in their own process groups distinct from the shell!
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98 | # bash: cat is in its own process group, but ps is in one with bash. Hm
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99 | ;;
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100 |
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101 | nested_eval)
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102 | echo '[nested eval]'
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103 | ps -o $PS_COLS | tac | eval 'cat | _tmp/cat2'
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104 | ;;
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105 |
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106 | nested_pipeline)
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107 | echo '[nested pipeline]'
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108 | ps -o $PS_COLS | { cat | _tmp/cat2; } | tac
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109 | ;;
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110 |
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111 | nested_pipeline_last)
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112 | echo '[nested pipeline]'
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113 | ps -o $PS_COLS | tac | { cat | _tmp/cat2; }
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114 | ;;
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115 |
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116 | *)
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117 | echo "Invalid snippet $snippet"
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118 | exit 1
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119 | ;;
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120 |
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121 | esac
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122 | }
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123 |
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124 | run_snippet() {
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125 | local sh=$1
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126 | local snippet=$2
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127 | local interactive=$3
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128 |
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129 | echo "run_snippet $sh $snippet $interactive"
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130 |
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131 | local tmp=_tmp/process-table.txt
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132 |
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133 | if test $interactive = 'yes'; then
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134 | # Run shell with -i, but source the code first.
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135 |
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136 | local more_flags=''
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137 | case $sh in
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138 | (bash|bin/osh)
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139 | more_flags='--rcfile /dev/null'
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140 | ;;
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141 | esac
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142 |
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143 | $sh $more_flags -i -c '. $0; show_process_table "$@"' $0 $sh $snippet > $tmp
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144 | else
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145 | # Run shell without -i.
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146 |
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147 | $sh $0 show_process_table $sh $snippet > $tmp
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148 | fi
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149 |
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150 | test/process_table.py $$ $sh $snippet $interactive < $tmp
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151 | local status=$?
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152 |
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153 | cat $tmp
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154 | echo
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155 |
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156 | return $status
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157 | }
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158 |
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159 | # We might be sourced by run_with_shell_interactive, so avoid running anything
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160 | # in that case.
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161 | case $1 in
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162 | setup|show_process_table|run_snippet)
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163 | "$@"
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164 | esac
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