gcc编译生成abc.o执行报错：Exec format error技术求助

Hey there! Let's clear up this confusion—it's a super common pitfall when you're getting familiar with GCC. Let's break down exactly what's happening with your commands and why you're seeing those errors.

First: The Difference Between Your Two GCC Commands #

You're using two similar-looking commands, but they do completely different things:

1. gcc abc.c -o abc.o
   This command runs both compilation AND linking in one step. Even though you named the output abc.o, this is actually a fully functional executable file. GCC doesn't care about the file extension here—it just follows your -o flag to name the output. That's why you can run it directly.

2. gcc abc.c -c
   The -c flag tells GCC to only run the compilation stage (turning your C code into assembly, then into machine code) but skip linking. The result is a relocatable object file—this is an intermediate file that contains your compiled code, but it's missing all the stuff needed to run as a standalone program:

   • It doesn't have the startup code that tells the OS how to launch your program
   • It hasn't been linked to system libraries (like libc which provides printf)
   • It's not formatted as an executable that the kernel can load

Why You're Seeing Those Errors #

Let's walk through each error:

• bash: ./abc.o: Permission denied: By default, GCC doesn't set executable permissions on object files (since they're not meant to be executed). Adding chmod +x fixes the permission issue, but...
• ./abc.o: cannot execute binary file: Exec format error: The file abc.o output confirms this—ELF 64-bit LSB relocatable means this is a relocatable object file, not an executable. Your OS knows it can't run this type of file, hence the error. Your architecture (x86_64) matches, but the file type is wrong.

The Correct Workflow #

If you want to split compilation and linking (useful for larger projects), here's how to do it properly:

1. Compile to object file:

   gcc abc.c -c -o abc.o
   

2. Link the object file into an executable:

   gcc abc.o -o abc
   

3. Now run the executable:

   ./abc
   

If you just want a quick executable without splitting stages, skip the -c flag and use a clearer name (no .o suffix to avoid confusion):

gcc abc.c -o abc
./abc

To confirm the difference, run file on both outputs:

• The executable from the first command will show ELF 64-bit LSB executable
• The object file from -c will show ELF 64-bit LSB relocatable

内容的提问来源于stack exchange，提问作者guapi