Redirect strace's output to file

You can use -o option to specify a file which saves strace's output:

# strace -o log.txt ls
log.txt
# more log.txt
execve("/usr/bin/ls", ["ls"], 0x7ffe2e59b220 /* 20 vars */) = 0
brk(NULL)                               = 0x5599582f6000
arch_prctl(0x3001 /* ARCH_??? */, 0x7fffd38db780) = -1 EINVAL (Invalid argument)
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
......

Additionally, -A option can be used to append log to an existing file instead of truncate it:

# ls -lth log.txt
-rw-r--r-- 1 root root 3.6K Feb 28 10:07 log.txt
# strace -o log.txt ls
log.txt
# ls -lth log.txt
-rw-r--r-- 1 root root 3.6K Feb 28 10:08 log.txt
# strace -A -o log.txt ls
log.txt
# ls -lth log.txt
-rw-r--r-- 1 root root 7.2K Feb 28 10:08 log.txt