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49 lines
1.8 KiB
Text
49 lines
1.8 KiB
Text
COMMENT(!MOD!zsh/clone
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A builtin that can clone a running shell onto another terminal.
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!MOD!)
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The tt(zsh/clone) module makes available one builtin command:
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startitem()
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findex(clone)
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cindex(shell, cloning)
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cindex(cloning the shell)
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cindex(terminal)
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item(tt(clone) var(tty))(
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Creates a forked instance of the current shell, attached to the specified
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var(tty). In the new shell, the tt(PID), tt(PPID) and tt(TTY) special
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parameters are changed appropriately. tt($!) is set to zero in the new
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shell, and to the new shell's PID in the original shell.
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The return status of the builtin is zero in both shells if successful,
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and non-zero on error.
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The target of tt(clone) should be an unused terminal, such as an unused virtual
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console or a virtual terminal created by
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example(xterm -e sh -c 'trap : INT QUIT TSTP; tty;
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while :; do sleep 100000000; done')
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Some words of explanation are warranted about this long xterm command
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line: when doing clone on a pseudo-terminal, some other session
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("session" meant as a unix session group, or SID) is already owning
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the terminal. Hence the cloned zsh cannot acquire the pseudo-terminal
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as a controlling tty. That means two things:
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startitemize()
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itemiz(the job control signals will go to the sh-started-by-xterm process
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group (that's why we disable INT QUIT and TSTP with trap; otherwise
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the while loop could get suspended or killed))
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itemiz(the cloned shell will have job control disabled, and the job
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control keys (control-C, control-\ and control-Z) will not work.)
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enditemize()
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This does not apply when cloning to an em(unused) vc.
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Cloning to a used (and unprepared) terminal will result in two
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processes reading simultaneously from the same terminal, with
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input bytes going randomly to either process.
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tt(clone) is mostly useful as a shell built-in replacement for
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openvt.
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)
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enditem()
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