10 “objcopy” Command Usage Examples in Linux

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This tutorial explains Linux “objcopy” command, options and its usage with examples.

objcopy – copy and translate object files

Description :

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objcopy uses the GNU BFD Library to read and write the object files. It can write the destination object file in a format different from that of the source object file. The exact behavior of objcopy is controlled by command-line options. Note that objcopy should be able to copy a fully linked file between any two formats. However, copying a relocatable object file between any two formats may not work as expected.

objcopy creates temporary files to do its translations and deletes them afterward. objcopy uses BFD to do all its translation work; it has access to all the formats described in BFD and thus is able to recognize most formats without being told explicitly.

objcopy can be used to generate S-records by using an output target of srec (e.g., use -O srec). objcopy can be used to generate a raw binary file by using an output target of binary (e.g., use -O binary). When objcopy generates a raw binary file, it will essentially produce a memory dump of the contents of the input object file. All symbols and relocation information will be discarded. The memory dump will start at the load address of the lowest section copied into the output file.

When generating an S-record or a raw binary file, it may be helpful to use -S to remove sections containing debugging information. In some cases -R will be useful to remove sections which contain information that is not needed by the binary file.

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Usage :

objcopy [options] infile [outfile]

Options :

–add-section section=file
Add a new section to the output object file with the specified section name and the contents taken from the specified file. Available only for formats that allow arbitrarily named sections.

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–alt-machine-code=n
If the output architecture has alternate machine codes, use the nth code instead of the default.

-b n, –byte=n
Copy only every nth byte. Header data is not affected. The value of n can be from 0 to interleave-1, where interleave is specified by -i (default is 4). This option is useful for creating files to program ROM and is typically used with srec as the output format.

-B bfdarch, –binary-architecture=bfdarch
Set the output architecture to bfdarch (e.g., i386) for transforming a raw binary file into an object file. Otherwise, this option is ignored. After the conversion, your program can access data inside the created object file by referencing the special symbols _binary_objfile_start, _binary_objfile_end, and _binary_objfile_size.

–change-addresses=incr, –adjust-vma=incr
Change the VMA and LMA addresses of all sections, plus the start address, by adding incr. Changing section addresses is not supported by all object formats. Sections are not relocated.

–change-leading-char
For object formats that use a special character (such as an underscore) to begin symbols, change the leading character when converting between formats. If the character is the same in both formats, the option has no effect. Otherwise, it adds, removes, or changes the leading character as appropriate for the output format.

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–change-section-address section{=|+|-}val,
–adjust-section-vma section{=|+|-}val
Set or change the VMA and LMA addresses of the specified section. With =, set the section address to the specified value; otherwise, add or subtract the value to get the new address.

–change-section-lma section{=|+|-}val
Set or change the LMA address of the specified section. With =, set the section address to the specified value; otherwise, add or subtract the value to get the new address.

–change-section-vma section{=|+|-}val
Set or change the VMA address of the specified section. With =, set the section address to the specified value; otherwise, add or subtract the value to get the new address.

–change-start incr, –adjust-start incr
Add incr to the start address to get a new start address. Not supported by all object formats.

–change-warnings, –adjust-warnings
Issue a warning if the section that is specified in one of the options –change-section-address, –change-section-lma, or –change-section-vma does not exist.

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–debugging
Convert debugging information if possible.

-F bfdname, –target=bfdname
Set the binary format for both input and output files to the binary file descriptor name bfdname. No format translation is done. Use the -h option for a list of supported formats for your system.

-g, –strip-debug
Do not copy debugging information.

-G symbol, –keep-global-symbol=symbol
Copy only the specified global symbol, making all other symbols local to the file. May be specified multiple times.

–gap-fill=val
Fill gaps between sections with the specified value; applies to the load address (LMA) of the sections.

-h, –help
Print help information, including a list of supported target object formats, then exit.

-i interleave, –interleave=interleave
Copy one out of every interleave bytes. Use -b to set the byte to copy (default is 4). This option is ignored if -b is not specified.

-I bfdname, –input-target=bfdname
Set the binary file format of the input file using its binary file descriptor name, bfdname.

-j section, –only-section=section
Copy only the specified section. May be specified multiple times.

-K symbol, –keep-symbol=symbol
Copy only the specified symbol from the source file. May be specified multiple times.

–keep-global-symbols=filename
Apply the option –keep-global-symbol to each symbol listed in the specified file. The file should have one symbol per line, with comments beginning with a hash mark (#). May be specified multiple times.

–keep-symbols=file
Apply the option –keep-symbol to each symbol listed in the specified file. The file should have one symbol per line, with comments beginning with a hash mark (#). May be specified multiple times.

-L symbol, –localize-symbol=symbol
Make the specified symbol local. May be specified multiple times.

–localize-symbols=filename
Apply the option –localize-symbol to each symbol listed in the specified file. The file should have one symbol per line, with comments beginning with a hash mark (#). May be specified multiple times.

-N symbol, –strip-symbol=symbol
Do not copy the specified symbol. May be specified multiple times.

–no-change-warnings, –no-adjust-warnings
Do not issue a warning even if the section specified in one of the options –change-section-address, –change-section-lma, or –change-section-vma does not exist.

-O bfdname, –output-target=bfdname
Set the binary file format of the output file using its binary file descriptor name, bfdname. The format srec generates S-records (printable ASCII versions of object files), and binary generates a raw binary file. Use -h for other available formats.

-p, –preserve-dates
Preserve the input file’s access and modification dates in the output file.

–pad-to=addr
Pad the output file up to the load address. Use the fill value specified by –gap-fill (default is 0).

-R section, –remove-section=section
Do not copy any section with the specified name. May be specified multiple times.

–redefine-sym old=new
Change the name of the symbol old to new.

–remove-leading-char
If the first character of a global symbol is a special character (such as an underscore) used by the input object file format, remove it. Unlike –change-leading-char, this option always changes the symbol name when appropriate, regardless of the output object format.

–rename-section oldname=newname[,flags] Rename a section from oldname to newname, optionally also changing the flags to flags.

-S, –strip-all
Do not copy relocation and symbol information.

–set-section-flags section=flags
Set flags for the specified section as a comma-separated string of flag names. Not all flags are meaningful for all object formats. The possible flags are alloc, code, contents, data, debug, load, noload, readonly, rom, and share.

–set-start=val
Set the start address of the new file to the specified value. Not supported by all object formats.

–srec-forceS3
Force all srec output records to be type S3 records.

–srec-len=ival
Set the maximum length of srec output records to the specified value. The length includes the address, data, and crc fields.

–strip-symbols=filename
Apply the option –strip-symbol to each symbol listed in the specified file. The file should have one symbol per line, with comments beginning with a hash mark (#). May be specified multiple times.

–strip-unneeded
Strip all symbols not needed for relocation processing.

-v, –verbose
Run in verbose mode, listing all object files modified; for archives, list all archive members.

-V, –version
Print version information and exit.

-W symbol, –weaken-symbol=symbol
Make the specified symbol weak. May be specified multiple times.

–weaken
Make all global symbols weak.

–weaken-symbols=filename
Apply the option –weaken-symbol to each symbol listed in the specified file. The file should have one symbol per line, with comments beginning with a hash mark (#). May be specified multiple times.

-x, –discard-all
Do not copy nonglobal symbols.

-X, –discard-locals
Do not copy compiler-generated local symbols (usually those starting with L or ..).

Examples :

1. Simply copy object file from source to destination

$ objcopy test new_test

So the above command will copy ‘test’ into a new file ‘new_test’. Note that since in this case, ‘test’ was compiled on the same platform so the output ‘new_test’ will be no different.

2. Copy the object file without providing the new file name

If no destination file name is supplied then the objcopy command replaces the original file with the copied file.

$ stat test
  File: `test'
  Size: 8498      	Blocks: 24         IO Block: 4096   regular file
Device: 805h/2053d	Inode: 1442357     Links: 1
Access: (0755/-rwxr-xr-x)  Uid: ( 1000/abc)   Gid: ( 1001/  family)
Access: 2012-08-31 21:25:54.828808055 +0530
Modify: 2012-08-31 21:25:50.498614487 +0530
Change: 2012-08-31 21:25:50.498614487 +0530
 
$ objcopy test
 
$ stat test
  File: `test'
  Size: 8498      	Blocks: 24         IO Block: 4096   regular file
Device: 805h/2053d	Inode: 1459714     Links: 1
Access: (0755/-rwxr-xr-x)  Uid: ( 1000/abc)   Gid: ( 1001/  family)
Access: 2012-08-31 21:30:04.108833244 +0530
Modify: 2012-08-31 21:30:04.108833244 +0530
Change: 2012-08-31 21:30:04.108833244 +0530

3. Remove only a particular section from the copied file using -R option

This option lets the objcopy command to copy the complete source file except the sections specified along with this option.

$ objcopy -R.interp test new_test

So we see that no .interp section is in the new file ‘new_test’.

4. Copy only a particular section using -j option

$ objcopy -j.interp test new_test

The above command will actually copy only .interp section into the empty new_test file. If we confirm it :

$ objdump -s new_test 
 
new_test:     file format elf64-x86-64
 
Contents of section .interp:
 400238 2f6c6962 36342f6c 642d6c69 6e75782d  /lib64/ld-linux-
 400248 7838362d 36342e73 6f2e3200           x86-64.so.2.
So we see that this file contains only .interp section (that we copied from ‘test).

5. Preserve the access and modification dates using -p option

$ objcopy -p test new_tst
 
$ stat test
  File: `test'
  Size: 8498      	Blocks: 24         IO Block: 4096   regular file
Device: 805h/2053d	Inode: 1459714     Links: 1
Access: (0755/-rwxr-xr-x)  Uid: ( 1000/abc)   Gid: ( 1001/  family)
Access: 2012-08-31 21:32:32.458629723 +0530
Modify: 2012-08-31 21:30:04.108833244 +0530
Change: 2012-08-31 21:30:04.108833244 +0530
 
$ stat new_tst
  File: `new_tst'
  Size: 8498      	Blocks: 24         IO Block: 4096   regular file
Device: 805h/2053d	Inode: 1442650     Links: 1
Access: (0755/-rwxr-xr-x)  Uid: ( 1000/abc)   Gid: ( 1001/  family)
Access: 2012-08-31 21:32:32.000000000 +0530
Modify: 2012-08-31 21:30:04.000000000 +0530
Change: 2012-08-31 21:42:25.938657423 +0530

So we see that both access and modification time/date was preserved.

6. Prefix symbols with a string using –prefix-symbols option

Consider the following example where a string ‘TUT’ is desired to be prefixed before symbol names :

$ objcopy --prefix-symbols="TUT" test new_test
$ readelf -s new_test
 
Symbol table '.dynsym' contains 4 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
     1: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND printf@GLIBC_2.2.5 (2)
     2: 0000000000000000     0 NOTYPE  WEAK   DEFAULT  UND __gmon_start__
     3: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __libc_start_main@GLIBC_2.2.5 (2)
 
Symbol table '.symtab' contains 65 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
     1: 0000000000400238     0 SECTION LOCAL  DEFAULT    1
     2: 0000000000400254     0 SECTION LOCAL  DEFAULT    2
     3: 0000000000400274     0 SECTION LOCAL  DEFAULT    3
     4: 0000000000400298     0 SECTION LOCAL  DEFAULT    4
     ...
    28: 000000000040046c     0 FUNC    LOCAL  DEFAULT   14 TUTcall_gmon_start
    29: 0000000000000000     0 FILE    LOCAL  DEFAULT  ABS TUTcrtstuff.c
    30: 0000000000600e18     0 OBJECT  LOCAL  DEFAULT   19 TUT__CTOR_LIST__
    31: 0000000000600e28     0 OBJECT  LOCAL  DEFAULT   20 TUT__DTOR_LIST__
    32: 0000000000600e38     0 OBJECT  LOCAL  DEFAULT   21 TUT__JCR_LIST__
    33: 0000000000400490     0 FUNC    LOCAL  DEFAULT   14 TUT__do_global_dtors_aux
    ...

7. Change all the global symbols to weak using –weaken option

This can be useful while building an object file that can be linked with other object files using the -R option to the linker.

$ readelf -s new_test
 
Symbol table '.dynsym' contains 4 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
     1: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND printf@GLIBC_2.2.5 (2)
     2: 0000000000000000     0 NOTYPE  WEAK   DEFAULT  UND __gmon_start__
     3: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __libc_start_main@GLIBC_2.2.5 (2)
 
Symbol table '.symtab' contains 65 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
     1: 0000000000400238     0 SECTION LOCAL  DEFAULT    1
     2: 0000000000400254     0 SECTION LOCAL  DEFAULT    2
     3: 0000000000400274     0 SECTION LOCAL  DEFAULT    3
     4: 0000000000400298     0 SECTION LOCAL  DEFAULT    4
     ..
    27: 0000000000000000     0 SECTION LOCAL  DEFAULT   27
    28: 000000000040046c     0 FUNC    LOCAL  DEFAULT   14 call_gmon_start
    29: 0000000000000000     0 FILE    LOCAL  DEFAULT  ABS crtstuff.c
    ..
    49: 0000000000400550     2 FUNC    GLOBAL DEFAULT   14 __libc_csu_fini
    50: 0000000000400440     0 FUNC    GLOBAL DEFAULT   14 _start
    51: 0000000000000000     0 NOTYPE  WEAK   DEFAULT  UND __gmon_start__
    52: 0000000000000000     0 NOTYPE  WEAK   DEFAULT  UND _Jv_RegisterClasses
    53: 0000000000400628     0 FUNC    GLOBAL DEFAULT   15 _fini
    54: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __libc_start_main@@GLIBC_
    55: 0000000000400638     4 OBJECT  GLOBAL DEFAULT   16 _IO_stdin_used
    ..
$ objcopy --weaken test new_test
 
$ readelf -s new_test
 
Symbol table '.dynsym' contains 4 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
     1: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND printf@GLIBC_2.2.5 (2)
     2: 0000000000000000     0 NOTYPE  WEAK   DEFAULT  UND __gmon_start__
     3: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __libc_start_main@GLIBC_2.2.5 (2)
 
Symbol table '.symtab' contains 65 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
     1: 0000000000400238     0 SECTION LOCAL  DEFAULT    1
     2: 0000000000400254     0 SECTION LOCAL  DEFAULT    2
     3: 0000000000400274     0 SECTION LOCAL  DEFAULT    3
     4: 0000000000400298     0 SECTION LOCAL  DEFAULT    4
     ..
    28: 000000000040046c     0 FUNC    LOCAL  DEFAULT   14 call_gmon_start
    29: 0000000000000000     0 FILE    LOCAL  DEFAULT  ABS crtstuff.c
    30: 0000000000600e18     0 OBJECT  LOCAL  DEFAULT   19 __CTOR_LIST__
    31: 0000000000600e28     0 OBJECT  LOCAL  DEFAULT   20 __DTOR_LIST__
    32: 0000000000600e38     0 OBJECT  LOCAL  DEFAULT   21 __JCR_LIST__
    ...
    49: 0000000000400550     2 FUNC    WEAK   DEFAULT   14 __libc_csu_fini
    50: 0000000000400440     0 FUNC    WEAK   DEFAULT   14 _start
    51: 0000000000000000     0 NOTYPE  WEAK   DEFAULT  UND __gmon_start__
    52: 0000000000000000     0 NOTYPE  WEAK   DEFAULT  UND _Jv_RegisterClasses
    53: 0000000000400628     0 FUNC    WEAK   DEFAULT   15 _fini
    54: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __libc_start_main@@GLIBC_
    55: 0000000000400638     4 OBJECT  WEAK   DEFAULT   16 _IO_stdin_used
    56: 0000000000601010     0 NOTYPE  WEAK   DEFAULT   25 __data_start
    ..

8. Prefix the section names with a string using –prefix-sections option

$ objcopy --prefix-sections="TUT" test new_test
$ readelf -s new_test
readelf: Error: no .dynamic section in the dynamic segment
 
Symbol table 'TUT.dynsym' contains 4 entries:
Num: Value          Size Type    Bind  Vis     Ndx Name
0: 0000000000000000 0    NOTYPE  LOCAL DEFAULT UND
...
...
...

9. Strip off a particular symbols using the –strip-symbols option

In case a some symbols need to be stripped then the option –strip-symbols can be used along with a file name. This file name contains the symbol names to be stripped (one in each line).

$ readelf -s new_test
 
Symbol table '.dynsym' contains 4 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
     1: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND printf@GLIBC_2.2.5 (2)
     2: 0000000000000000     0 NOTYPE  WEAK   DEFAULT  UND __gmon_start__
     3: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __libc_start_main@GLIBC_2.2.5 (2)
 
Symbol table '.symtab' contains 65 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
     1: 0000000000400238     0 SECTION LOCAL  DEFAULT    1
     2: 0000000000400254     0 SECTION LOCAL  DEFAULT    2
     3: 0000000000400274     0 SECTION LOCAL  DEFAULT    3
     4: 0000000000400298     0 SECTION LOCAL  DEFAULT    4
     .....
    28: 000000000040046c 0 FUNC LOCAL DEFAULT 14 call_gmon_start
    29: 0000000000000000     0 FILE    LOCAL  DEFAULT  ABS crtstuff.c
    30: 0000000000600e18     0 OBJECT  LOCAL  DEFAULT   19 __CTOR_LIST__
    31: 0000000000600e28     0 OBJECT  LOCAL  DEFAULT   20 __DTOR_LIST__
    32: 0000000000600e38     0 OBJECT  LOCAL  DEFAULT   21 __JCR_LIST__
    33: 0000000000400490     0 FUNC    LOCAL  DEFAULT   14 __do_global_dtors_aux
    ...
 
$ objcopy --strip-symbols=symbolname test new_test
 
$ readelf -s new_test
 
Symbol table '.dynsym' contains 4 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
     1: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND printf@GLIBC_2.2.5 (2)
     2: 0000000000000000     0 NOTYPE  WEAK   DEFAULT  UND __gmon_start__
     3: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __libc_start_main@GLIBC_2.2.5 (2)
 
Symbol table '.symtab' contains 64 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
     1: 0000000000400238     0 SECTION LOCAL  DEFAULT    1
     2: 0000000000400254     0 SECTION LOCAL  DEFAULT    2
     3: 0000000000400274     0 SECTION LOCAL  DEFAULT    3
     4: 0000000000400298     0 SECTION LOCAL  DEFAULT    4
     ...
    26: 0000000000601020     0 SECTION LOCAL  DEFAULT   26
    27: 0000000000000000     0 SECTION LOCAL  DEFAULT   27
    28: 0000000000000000     0 FILE    LOCAL  DEFAULT  ABS crtstuff.c
    29: 0000000000600e18     0 OBJECT  LOCAL  DEFAULT   19 __CTOR_LIST__
    30: 0000000000600e28     0 OBJECT  LOCAL  DEFAULT   20 __DTOR_LIST__
    31: 0000000000600e38     0 OBJECT  LOCAL  DEFAULT   21 __JCR_LIST__
    32: 0000000000400490     0 FUNC    LOCAL  DEFAULT   14 __do_global_dtors_aux
    ...

So we see that the symbol ‘call_gmon_start’ was stripped off successfully.

10. Retain source file name symbol using –keep-file-symbols option

$ objcopy --strip-debug test new_test
$ readelf -s new_test
 
Symbol table '.dynsym' contains 4 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
     1: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND printf@GLIBC_2.2.5 (2)
     2: 0000000000000000     0 NOTYPE  WEAK   DEFAULT  UND __gmon_start__
     3: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __libc_start_main@GLIBC_2.2.5 (2)
 
Symbol table '.symtab' contains 62 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
     1: 000000000040046c     0 FUNC    LOCAL  DEFAULT   14 call_gmon_start
     2: 0000000000600e18     0 OBJECT  LOCAL  DEFAULT   19 __CTOR_LIST__
     3: 0000000000600e28     0 OBJECT  LOCAL  DEFAULT   20 __DTOR_LIST__
     4: 0000000000600e38     0 OBJECT  LOCAL  DEFAULT   21 __JCR_LIST__
     ...
    10: 00000000004006e8     0 OBJECT  LOCAL  DEFAULT   18 __FRAME_END__
    11: 0000000000600e38     0 OBJECT  LOCAL  DEFAULT   21 __JCR_END__
    12: 00000000004005f0     0 FUNC    LOCAL  DEFAULT   14 __do_global_ctors_aux
    13: 0000000000600fe8     0 OBJECT  LOCAL  HIDDEN   24 _GLOBAL_OFFSET_TABLE_
    14: 0000000000600e14     0 NOTYPE  LOCAL  HIDDEN   19 __init_array_end
    15: 0000000000600e14     0 NOTYPE  LOCAL  HIDDEN   19 __init_array_start
    ...
 
$ objcopy --strip-debug --keep-file-symbols test new_test
 
$ readelf -s new_test
 
Symbol table '.dynsym' contains 4 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
     1: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND printf@GLIBC_2.2.5 (2)
     2: 0000000000000000     0 NOTYPE  WEAK   DEFAULT  UND __gmon_start__
     3: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __libc_start_main@GLIBC_2.2.5 (2)
 
Symbol table '.symtab' contains 65 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
     1: 000000000040046c     0 FUNC    LOCAL  DEFAULT   14 call_gmon_start
     2: 0000000000000000     0 FILE    LOCAL  DEFAULT  ABS crtstuff.c
     3: 0000000000600e18     0 OBJECT  LOCAL  DEFAULT   19 __CTOR_LIST__
     4: 0000000000600e28     0 OBJECT  LOCAL  DEFAULT   20 __DTOR_LIST__
     ...
    12: 00000000004006e8     0 OBJECT  LOCAL  DEFAULT   18 __FRAME_END__
    13: 0000000000600e38     0 OBJECT  LOCAL  DEFAULT   21 __JCR_END__
    14: 00000000004005f0     0 FUNC    LOCAL  DEFAULT   14 __do_global_ctors_aux
    15: 0000000000000000 0 FILE LOCAL DEFAULT ABS test.c
    16: 0000000000600fe8     0 OBJECT  LOCAL  HIDDEN   24 _GLOBAL_OFFSET_TABLE_
    17: 0000000000600e14     0 NOTYPE  LOCAL  HIDDEN   19 __init_array_end
    18: 0000000000600e14     0 NOTYPE  LOCAL  HIDDEN   19 __init_array_start
    ...

In the above example, firstly the objcopy was run with –strip-debug option which (along with many other symbols) stripped off the symbol mentioning source file (test.c) name. Next we re-run the objcopy command along with the –keep-file-symbols option and observe that symbol for source file name was not stripped off.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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