NAME

symbols — display symbol information about a file or process

SYNOPSIS

symbols [-help] [-w] [-uuid] [-arch arch_name] [-saveSignature path] [-symbolsPackageDir path] [-lookup (0x1234 | symbol) ...] [-dedup] file... pid... process-name... signature... dSYM...

DESCRIPTION

The symbols command may be used to examine library, symbol, and source line information in files and running processes.

You may need root privileges to examine running processes.

The symbols command can be used to determine symbol availability to tools such as Instruments, dtrace, and sample.

COMMON OPTIONS

-help: Print a more extensive list of options
-v: Print version information
-w: Print wide output, do not clip to terminal width
-uuid: Print UUID info only.
-arch arch_name: Specify the target architecture. The default value is current , which matches the current system architecture. If the current architecture is not available in the targeted file or process, the symbols command will attempt to use any64bit , which matches the first available 64-bit architecture. If there is no 64-bit architecture available, the symbols command will finally fall back to any , which matches the first available architecture. The value all may be used to iterate over all architectures in a target. The arch name may also be any of the commonly used architecture mnemonics, for example i386, x86_64, or arm
-cpuType #: Specify the target architecture cpu type as a numeric value
-cpuSubtype #: Specify the target architecture cpu subtype as a numeric value
-noHeaders: Do not print library level information. This also suppresses printing of any lower level information, which implies -noRegions, -noSymbols, and -noSources
-noRegions: Do not print segment/section level information. This also suppresses printing of any lower level information, which implies -noSymbols and -noSources
-noSymbols: Do not print symbol level information. This also suppresses printing of any lower level information, which implies -noSources
-noSources: Do not print source level information
-noDemangling: Do not print the human readable form of symbol names, instead print the name used by the linker
-printSignature: Print a "signature" for each target, which can later be used as input to the symbols command. This is a way to archive target data for later use. See also the -saveSignature flag
-deepSignature: Causes all signatures to be "deep copies", containing complete copies of all available information
-fullSourcePath: Print the entire source path for each source info
-printDsymPaths: Print the path of the dSYM file (if found) used when creating symbol information
-lookup (0x1234 | symbol): Find one or more addresses or symbols in the targets. Symbols may contain simple shell globbing style patterns.
-dedup: Print all variants for <deduplicated_symbol>. Deduplicated symbols are the result of linker optimization that unites functions with identical instructions into one symbol, i.e. deduplicates them. The original function variants are deduced from the Nlist.

OUTPUT

Output from symbols has the following format:

target [arch_name, elapsed-time]:
UUID symbol-owner-path [FLAGS]
address (size) region-name
address (size) symbol-name [FLAGS]
address (size) sourcefile : line #

Symbol owner flags have the following meanings:

PROT: A load command has the SG_PROTECTED_VERSION_1 flag set
AOUT: This symbol owner is an executable
DYLIB: This symbol owner is a dylib or framework
DYLIB-STUB: This symbol owner is used only by the linker
DYLD: This symbol owner is the runtime dynamic linker
BUNDLE: This symbol owner is a loadable bundle
OBJECT: This symbol owner is an unlinked object file
KEXT-BUNDLE: This symbol owner is a kext
dSYM_v#: This symbol owner is a dSYM, of version '#'
DYLDSHAREDCACHE: This symbol owner was found in the dyld shared cache
ObjC-RR: This symbol owner supports manual retain-release
ObjC-GC: This symbol owner supports old-style garbage collection
SLID: This symbol owner was relocated from its base address
PIE: This symbol owner is compiled position independent
RESTRICTED: This symbol owner has a restrict segment/section
STATIC-LIB: This symbol-owner is from a static library (.a)
FaultedFromDisk: The data for this symbol owner was found on disk
FaultedFromTask: The data for this symbol owner was retrieved from a running task
FaultedFromSelfDyldSharedCache: The data for this symbol owner was found in the current processes dyld shared cache
FilesetEntry: This symbol owner is a member of a fileset kernel collection
Found-dSYM: A dSYM was found for this symbol owner
Found-Binary-via-dSYM-colocation: The binary for this symbol owner was found by looking up the dSYM, and then looking next to the dSYM
Found-Binary-via-dSYM-plist: The binary for this symbol owner was found by looking up the dSYM, and then reading its plist
MMap32: The symbol owner is using a mmap'd file cache for symbol information
MMap64: The symbol owner is using a mmap'd file cache for symbol information
Private: This symbol owner cannot be cached
Empty: No data was found for this symbol owner

Symbol flags have the following meanings:

FUNC: This symbol has executable code
DYLD-STUB: This symbol is a stub used by the dynamic linker
OBJC: This symbol is an Objective C method
THUMB: This symbol uses thumb instruction encoding
OMIT-FP: This symbol does not create a frame pointer.
EXT: This symbol has external visibility
PEXT: This symbol has private-external visibility
LENGTH: The length of this symbol is known, not guessed
NameNList: The name of this symbol comes from NList data
NameDwarf: The name of this symbol comes from Dwarf data
NameDwarfMIPSLinkage: The name of this symbol is from specialized Dwarf
MangledNameNList: The mangled name of this symbol is from NList data
MangledNameDwarf: The mangled name of this symbol is from Dwarf data
MangledNameDwarfMIPSLinkage: The mangled name of this symbol is from specialized Dwarf
Merged: This symbol has multiple data sources
NList: This symbol was found in NList data
Dwarf: This symbol was found in Dwarf data
DebugMap: This symbol was found in DebugMap data
FunctionStarts: This symbol was found in function starts data
DEDUP: This symbol the outcome of code deduplication linker optimization

SOURCES OF SYMBOL INFORMATION

symbols uses multiple sources of symbol information. All sources are queried, and the resulting data is merged.

NLIST symbol information is found in the LINKEDIT segment. It is imprecise, and only contains a starting address, not a length or ending address. Nlist data is not required to (and typically does not) reference all symbols. Usually only external symbol information is available. Even that may be removed by use of strip(1)

DEBUG MAP symbol information is multi-part. A per-symbol reference in the original file points to an external file containing additional debug information, usually DWARF.

FUNCTION STARTS symbol information is found in the LC_FUNCTION_STARTS load command of the target. It is imprecise, and only contains a starting address, not a length or ending address. Furthermore, it contains no name or mangled name information. The LC_FUNCTION_STARTS load command is optional, it may not be found in all targets.

DWARF symbol information is true debug info. It is usually precise (but it is not required to be). When available, dwarf information is treated as more reliable than any other information source, and conflicts are resolved in favor of dwarf data.

DSYM. A dSYM is an external file containing DWARF and NLIST symbol information.

KERNEL SYMBOLS

Kernel symbols are available by using the special pid "-1". This includes loaded kexts.

SIGNATURES

A signature is the information needed to reconstruct symbol information at a later date. For example, a signature contains a list of libraries, and for each library a UUID and the addresses the segments were loaded at. You can also ask for a "deep" signature, which contains complete information about every piece of information symbols could find. This can be very useful for later diagnosis and exploration.

SYMBOLS PACKAGE

A symbols package is a directory with "deep" signatures for one or more binary images. When a directory is specified with -symbolsPackageDir, symbols will output a deep signature for each binary image slice it reads. These files contain enough information to symbolicate application stack traces (such as those generated by crash reports) with function names and file names/line numbers.

EXAMPLES

symbols /System/Library/Frameworks/AppKit.framework/AppKit: Print out all symbol and source line information in the default architecture of AppKit.
symbols -uuid /System/Library/Frameworks/AppKit.framework/AppKit: Print out summarized UUID information for each arch in AppKit.
symbols -arch i386 /System/Library/Frameworks/AppKit.framework/AppKit: Print out all symbol and source line information in the i386 architecture of AppKit.
symbols 7085: Print out all symbol and source line information in pid 7085.
symbols 7085 -lookup 0x7fff5bf0008: Print the symbol and source line information in pid 7085 at address 0x7fff5bf0008.
symbols Safari: Attempt to find a process named Safari, and print its symbol and source line information.
symbols -deepSignature -saveSignature /tmp/Safari.signature Safari: Attempt to find a process named Safari, and save a copy of all discoverable information to a file in /tmp.
symbols /tmp/Safari.signature -lookup "*alloc*": Using the cached information in /tmp/Safari.signature, find every method/function matching the wildcard name *alloc*
symbols -w -1: Print out in wide format all available information on kernel symbols