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                        <'                 -d seconds      # trace duration, and use buffers\n'>
                        <'                 -p PID          # PID to match on event\n'>
                        <'                 -L TID          # thread id to match on event\n'>
                        <'                 -v              # view format file (don\'t trace)\n'>
                        <'                 -H              # include column headers\n'>
                        <'                 -l              # list all tracepoints\n'>
                        <'                 -s              # show kernel stack traces\n'>
                        <'                 -h              # this usage message\n'>
                        <'   eg,\n'>
                        <'       tpoint -l | grep open\n'>
                        <'                                 # find tracepoints containing '>
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                        <'       tpoint syscalls:sys_enter_open\n'>
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                        <'       tpoint block:block_rq_issue\n'>
                        <'                                 # trace block I/O issue\n'>
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                        <'See the man page and example file for more info.\n'>
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                          (DQ <'WARNING: command failed '> 
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                  action: [(C {<usage>})]
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                  action: [
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    (command.AndOr
      ops: [Id.Op_DPipe]
      children: [
        (C {<cd>} {($ Id.VSub_DollarName '$tracing')})
        (C {<die>} 
          {
            (DQ <'ERROR: accessing tracing. Root user? Kernel has FTRACE?\n'> 
              <'    debugfs mounted? (mount -t debugfs debugfs /sys/kernel/debug)'>
            )
          }
        )
      ]
    )
    (command.If
      arms: [
        (if_arm
          cond: 
            (condition.Shell
              commands: [
                (command.Sentence
                  child: (command.DParen child:<Id.Lit_ArithVarLike opt_list>)
                  terminator: <Id.Op_Semi _>
                )
              ]
            )
          action: [
            (C {<cd>} {<events>})
            (command.ForEach
              iter_name: tp
              iter_words: [{<Id.Lit_Star '*'> <'/'> <Id.Lit_Star '*'>}]
              do_arg_iter: F
              body: 
                (command.DoGroup
                  children: [
                    (command.AndOr
                      ops: [Id.Op_DAmp]
                      children: [
                        (command.DBracket
                          expr: 
                            (bool_expr.Unary
                              op_id: Id.BoolUnary_f
                              child: {($ Id.VSub_DollarName '$tp')}
                            )
                        )
                        (command.ControlFlow
                          token: <Id.ControlFlow_Continue continue>
                        )
                      ]
                    )
                    (C {<echo>} 
                      {
                        (braced_var_sub
                          token: <Id.VSub_Name tp>
                          suffix_op: 
                            (suffix_op.PatSub
                              pat: {(word_part.EscapedLiteral token:<Id.Lit_EscapedChar '\\/'>)}
                              replace: {<':'>}
                              replace_mode: Id.Undefined_Tok
                            )
                        )
                      }
                    )
                  ]
                )
            )
            (command.ControlFlow token:<Id.ControlFlow_Exit exit>)
          ]
          spids: [901 911]
        )
      ]
    )
    (command.ShAssignment
      pairs: [
        (assign_pair
          lhs: (sh_lhs_expr.Name name:tdir)
          op: assign_op.Equal
          rhs: 
            {<'events/'> 
              (braced_var_sub
                token: <Id.VSub_Name tpoint>
                suffix_op: 
                  (suffix_op.PatSub
                    pat: {<':'>}
                    replace: {(word_part.EscapedLiteral token:<Id.Lit_EscapedChar '\\/'>)}
                    replace_mode: Id.Undefined_Tok
                  )
              )
            }
          spids: [972]
        )
      ]
    )
    (command.AndOr
      ops: [Id.Op_DPipe]
      children: [
        (command.DBracket
          expr: (bool_expr.Unary op_id:Id.BoolUnary_e child:{($ Id.VSub_DollarName '$tdir')})
        )
        (C {<die>} 
          {(DQ <'ERROR: tracepoint '> ($ Id.VSub_DollarName '$tpoint') <' not found. Exiting'>)}
        )
      ]
    )
    (command.If
      arms: [
        (if_arm
          cond: 
            (condition.Shell
              commands: [
                (command.Sentence
                  child: (command.DParen child:<Id.Lit_ArithVarLike opt_view>)
                  terminator: <Id.Op_Semi _>
                )
              ]
            )
          action: [
            (C {<cat>} {($ Id.VSub_DollarName '$tdir') <'/format'>})
            (command.ControlFlow token:<Id.ControlFlow_Exit exit>)
          ]
          spids: [1004 1014]
        )
      ]
    )
    (command.AndOr
      ops: [Id.Op_DAmp]
      children: [
        (command.DBracket
          expr: (bool_expr.Unary op_id:Id.BoolUnary_e child:{($ Id.VSub_DollarName '$flock')})
        )
        (C {<die>} 
          {
            (DQ <'ERROR: ftrace may be in use by PID '> 
              (command_sub
                left_token: <Id.Left_DollarParen '$('>
                child: (C {<cat>} {($ Id.VSub_DollarName '$flock')})
              ) <' '> ($ Id.VSub_DollarName '$flock')
            )
          }
        )
      ]
    )
    (command.AndOr
      ops: [Id.Op_DPipe]
      children: [
        (command.Simple
          words: [{<echo>} {($ Id.VSub_Dollar '$$')}]
          redirects: [
            (redir
              op: <Id.Redir_Great '>'>
              loc: (redir_loc.Fd fd:1)
              arg: {($ Id.VSub_DollarName '$flock')}
            )
          ]
          do_fork: T
        )
        (C {<die>} {(DQ <'ERROR: unable to write '> ($ Id.VSub_DollarName '$flock') <.>)})
      ]
    )
    (command.ShAssignment
      pairs: [
        (assign_pair
          lhs: (sh_lhs_expr.Name name:wroteflock)
          op: assign_op.Equal
          rhs: {<1>}
          spids: [1072]
        )
      ]
    )
    (command.Simple
      words: [{<echo>} {<nop>}]
      redirects: [(redir op:<Id.Redir_Great '>'> loc:(redir_loc.Fd fd:1) arg:{<current_tracer>})]
      do_fork: T
    )
    (command.If
      arms: [
        (if_arm
          cond: 
            (condition.Shell
              commands: [
                (command.Sentence
                  child: (command.DParen child:<Id.Lit_ArithVarLike opt_filter>)
                  terminator: <Id.Op_Semi _>
                )
              ]
            )
          action: [
            (command.If
              arms: [
                (if_arm
                  cond: 
                    (condition.Shell
                      commands: [
                        (command.Sentence
                          child: 
                            (command.Pipeline
                              children: [
                                (command.Simple
                                  words: [{<echo>} {(DQ ($ Id.VSub_DollarName '$filter'))}]
                                  redirects: [
                                    (redir
                                      op: <Id.Redir_Great '>'>
                                      loc: (redir_loc.Fd fd:1)
                                      arg: {($ Id.VSub_DollarName '$tdir') <'/filter'>}
                                    )
                                  ]
                                  do_fork: T
                                )
                              ]
                              negated: T
                            )
                          terminator: <Id.Op_Semi _>
                        )
                      ]
                    )
                  action: [(C {<edie>} {(DQ <'ERROR: setting filter or -p. Exiting.'>)})]
                  spids: [1100 1116]
                )
              ]
            )
          ]
          spids: [1087 1097]
        )
      ]
    )
    (command.If
      arms: [
        (if_arm
          cond: 
            (condition.Shell
              commands: [
                (command.Sentence
                  child: (command.DParen child:<Id.Lit_ArithVarLike opt_stack>)
                  terminator: <Id.Op_Semi _>
                )
              ]
            )
          action: [
            (command.If
              arms: [
                (if_arm
                  cond: 
                    (condition.Shell
                      commands: [
                        (command.Sentence
                          child: 
                            (command.Pipeline
                              children: [
                                (command.Simple
                                  words: [{<echo>} {<1>}]
                                  redirects: [
                                    (redir
                                      op: <Id.Redir_Great '>'>
                                      loc: (redir_loc.Fd fd:1)
                                      arg: {<'options/stacktrace'>}
                                    )
                                  ]
                                  do_fork: T
                                )
                              ]
                              negated: T
                            )
                          terminator: <Id.Op_Semi _>
                        )
                      ]
                    )
                  action: [(C {<edie>} {(DQ <'ERROR: enabling stack traces (-s). Exiting'>)})]
                  spids: [1143 1156]
                )
              ]
            )
          ]
          spids: [1130 1140]
        )
      ]
    )
    (command.If
      arms: [
        (if_arm
          cond: 
            (condition.Shell
              commands: [
                (command.Sentence
                  child: 
                    (command.Pipeline
                      children: [
                        (command.Simple
                          words: [{<echo>} {<1>}]
                          redirects: [
                            (redir
                              op: <Id.Redir_DGreat '>>'>
                              loc: (redir_loc.Fd fd:1)
                              arg: {($ Id.VSub_DollarName '$tdir') <'/enable'>}
                            )
                          ]
                          do_fork: T
                        )
                      ]
                      negated: T
                    )
                  terminator: <Id.Op_Semi _>
                )
              ]
            )
          action: [
            (C {<edie>} 
              {(DQ <'ERROR: enabling tracepoint '> ($ Id.VSub_DollarName '$tprobe') <'. Exiting.'>)}
            )
          ]
          spids: [1170 1184]
        )
      ]
    )
    (C {<warn>} {(DQ <'echo > trace'>)})
    (command.If
      arms: [
        (if_arm
          cond: 
            (condition.Shell
              commands: [
                (command.Sentence
                  child: (command.DParen child:<Id.Lit_ArithVarLike opt_duration>)
                  terminator: <Id.Op_Semi _>
                )
              ]
            )
          action: [
            (C {<sleep>} {($ Id.VSub_DollarName '$duration')})
            (command.If
              arms: [
                (if_arm
                  cond: 
                    (condition.Shell
                      commands: [
                        (command.Sentence
                          child: (command.DParen child:<Id.Lit_ArithVarLike opt_headers>)
                          terminator: <Id.Op_Semi _>
                        )
                      ]
                    )
                  action: [(C {<cat>} {<trace>})]
                  spids: [1225 1235]
                )
              ]
              else_action: [(C {<grep>} {<-v>} {(SQ <'^#'>)} {<trace>})]
            )
          ]
          spids: [1207 1217]
        )
      ]
      else_action: [
        (command.AndOr
          ops: [Id.Op_DAmp]
          children: [(command.DParen child:<Id.Lit_ArithVarLike opt_headers>) (C {<cat>} {<trace>})]
        )
        (C {<cat>} {<trace_pipe>})
      ]
    )
    (C {<end>})
  ]
)