commands.md

Commands

Some commands to inspect .data, .bss, and .rodata sections in a compiled Rust (or C) program using standard Linux command-line tools. You can use grep on the output files to search for your uniquely named string literals or variable names, such as FIRST_CONST or SECOND, to confirm where they are stored in memory. To learn more about the commands you can use run man readelf, or man objdump to read the manuals - or you could use google.

First, compile the Rust program to a binary:

rustc -C opt-level=0 -C debuginfo=0 src/main.rs -o target_binary

• -C opt-level=0 disables optimizations to preserve symbols.
• -C debuginfo=0 omits debug info to keep the binary minimal.

To list all sections in the binary:

readelf -S ./target_binary > out-readelf-sections

• -S prints section headers from the ELF file.
• Look/search for the .data, .bss, .rodata sections.

To view the contents of the read-only data segment:

objdump -s -j .rodata ./target_binary > out-objdump-rodata

• -s dumps section contents.
• -j .rodata specifies the .rodata segment.

To view the contents of the initialized writable data segment:

objdump -s -j .data ./target_binary > out-objdump-data

• Same as above, but for .data.
• Not easy to interpret as is pointer and integer not characters

To view zero-initialized statics (metadata only):

objdump -s -j .bss ./target_binary > out-objdump-bss

• .bss will be empty / zeroed out as it is data that is zero-initialised.

To list global symbols and their segment classification:

nm -C ./target_binary > out-nm

• -C demangles Rust symbol names for readability.

To confirm if .bss is present and see its size:

readelf -S ./target_binary | grep .bss > out-bss-section

Summary of segment purposes:

Segment	Purpose	Writable	In File
.rodata	Constants, string literals	No	Yes
.data	Initialized static/global variables	Yes	Yes
.bss	Zero-initialized static/global vars	Yes	No (size only)