DYLD_USAGE(1) dyld DYLD_USAGE(1)

dyld_usage - report dynamic linker activity in real-time

dyld_usage [-e] [-f mode] [-j] [-h] [-t seconds] [-R rawfile [-S start_time] [-E end_time]] [pid | cmd [pid | cmd] ...]

The dyld_usage utility presents an ongoing display of information pertaining to dynamic linker activity within one or more processes. It requires root privileges due to the kernel tracing facility it uses to operate. By default dyld_usage monitors dyld activity in all processes except the running dyld_usage process, Terminal, telnetd, sshd, rlogind, tcsh, csh, and sh. These defaults can be overridden such that output is limited to include or exclude a list of processes specified on the command line. Processes may be specified either by file name or by process id.

The output of dyld_usage is formatted according to the size of your window. A narrow window will display fewer columns of data. Use a wide window for maximum data display.

dyld_usage supports the following options:

Exclude the specified list of pids and commands from the sample, and exclude dyld_usage by default.

Display output in JSON format.


Display usage information and exit.

Specify a raw trace file to process.

Specify timeout in seconds (for use in automated tools).

The data columns displayed are as follows:

Time of day when call occurred.
The dyld operation triggered by the process. Typically these operations are triggered by process launch or via a dlopen or dlsym system call. System call entries include both the parameters to the system call and the system call's return code (e.g., 0 on success).
The elapsed time spent in the dynamic linker operation or system call.
The process that generated the dynamic linker activity. If space allows, the thread id will be appended to the process name (i.e., Mail.nnn).



sudo dyld_usage Mail

dyld_usage will display dynamic link operations for all instances of processes named Mail.



dyld(1), fs_usage(1)

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2020-04-13