1516ff1550
Make the pid parameter default to the PID of the current process. Change the exit code for invalid arguments to a value in the user defined range (see https://tldp.org/LDP/abs/html/exitcodes.html). This may be considered a breaking change, but since the only applications that currently use this script don't rely on this code, I don't think we need to bump the major version for this.
65 lines
1.4 KiB
Bash
Executable File
65 lines
1.4 KiB
Bash
Executable File
#!/bin/bash
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USAGE='
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USAGE: rpid <pid|-h|-[-]help> [<root_name>=login]
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pid The PID of the process for which you want to find the root
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PID. Defaults to $$.
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root_name
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The name (not command line) of the root process, for which
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to find the PID. Defaults to login.
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EXAMPLES:
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Any of these will display this help message.
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rpid -h
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rpid -help
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rpid --help
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Get the PID of the login process that is the ancestor of the current
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process.
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rpid
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'
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# Validate the arguments
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if [[ "$#" -gt 2 ]]; then
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printf '%s' "${USAGE}" 1>&2
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exit 64
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fi
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pid="${1:-$$}"
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# Check if the user needs help
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if [[ "${pid}" =~ ^(-h|-(-)?help)$ ]]; then
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printf '%s' "${USAGE}" 1>&2
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exit 0
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fi
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root_name="${2:-login}"
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get_info() {
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local -ri current_pid="$1"
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if [[ ! -r "/proc/${current_pid}/status" ]]; then exit 1; fi
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mapfile info < \
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<(grep --null -E -m 2 '^(Name|PPid):' "/proc/${current_pid}/status" \
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| sort | cut -f 2)
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name="${info[0]##[[:space:]]}"
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name="${name%%[[:space:]]}"
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ppid="${info[1]##[[:space:]]}"
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ppid="${ppid%%[[:space:]]}"
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}
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next_pid="${pid}"
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while [[ "${name}" != "${root_name}" && "${ppid}" -ne 1 ]]; do
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get_info "${next_pid}";
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name_pid="${next_pid}"
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next_pid="${ppid}"
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done
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if [[ "${name}" != "${root_name}" ]]; then exit 1; fi
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printf '%s\n' "${name_pid}"
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