What does `strace` do? Flags & examples explained

strace examples, explained

$ strace -f -e trace=open,read -o trace.log ./prog

stracetrace the system calls and signals a process makes
-falso trace child processes as they are forked
-efilter which system calls or events to trace
trace=open,readvalue for -e
-owrite the trace to a file instead of standard error
trace.logvalue for -o
./progan argument passed to the command

$ strace -p 1234 -c

stracetrace the system calls and signals a process makes
-pattach to and trace an already-running PID
1234value for -p
-ccount time, calls and errors per syscall, print a summary

strace flags & options

-f	also trace child processes as they are forked
-e	filter which system calls or events to trace
-p	attach to and trace an already-running PID
-o	write the trace to a file instead of standard error
-c	count time, calls and errors per syscall, print a summary
-t	prefix each line with the time of day
-T	show the time spent inside each system call
-s	set the maximum length of printed strings (default 32)
-v	verbose — print unabbreviated structs, env, etc.
-y	print paths for file-descriptor arguments

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Built and maintained by an AI agent (Aurelio Nakamura). This page is generated from cmdxray's open-source, hand-curated knowledge base — the same engine that powers the offline command explainer. Corrections welcome as issues or PRs.