function::task_fd_lookup - Linux
Overview
function::task_fd_lookup
is a command used in the Linux kernel for looking up file descriptors associated with a task. It is primarily used for debugging and diagnostic purposes, providing information about open files and their status within a specific task.
Syntax
function::task_fd_lookup [options] <task_pid>
Parameters
<task_pid>
: Task ID for which file descriptors are to be looked up.
Options/Flags
| Option | Description |
|—|—|
| -c
| Count open file descriptors. |
| -d
| Dump file descriptor information in detail. |
| -D
| Dump all file descriptors. |
| -f
| Force lookup, even if task is not running. |
| -h
| Display usage help. |
| -k
| Use kernel symbols for dump output. |
| -l
| List open file descriptor numbers. |
| -m
| Dump memory mapped file information. |
| -n
| Display file descriptor numbers only. |
| -P
| Dump poll table information. |
| -r
| Dump read-only file descriptor information. |
| -s
| Dump signal handlers. |
| -T
| Dump thread group information. |
| -t
| Dump threads. |
| -u
| Dump user space information. |
| -v
| Verbose output. |
Examples
Simple Usage:
function::task_fd_lookup 1234
This lists the file descriptors open by the task with ID 1234.
Count Open File Descriptors:
function::task_fd_lookup -c 1234
This counts and displays the number of open file descriptors for the task.
Detailed Information Dump:
function::task_fd_lookup -D 1234
This dumps detailed information about all file descriptors open by the task.
Common Issues
- Permission denied: Ensure you have sufficient privileges to access the task information.
- Task not found: The specified task ID may not exist or the task may have terminated before the command was executed.
Integration
function::task_fd_lookup
can be integrated with other commands or tools for advanced debugging tasks:
ps
:ps -p <task_pid> -aux | function::task_fd_lookup <task_pid>
: Display process information and open file descriptors for a specific task.strace
:strace -p <task_pid> | function::task_fd_lookup <task_pid>
: Trace system calls and correlate them with open file descriptors.lsof
:lsof -p <task_pid> | function::task_fd_lookup <task_pid>
: List open files by a specific task and cross-reference them with the file descriptor information.
Related Commands
lsof
: Lists open files by process.strace
: Traces system calls made by a process.pmap
: Displays memory map of a process.