In Chapter 5.5, there is one step that fixes the GCC's stack protection detection problem. The command is:
sed -i '/k prot/agcc_cv_libc_provides_ssp=yes' gcc/configure
This command seems weird to me at first glance. After digging a little more
about sed command, it's intention is much clear.
-
-i means change the file (i.e.,
gcc/configure) in place -
/k prot/ is the pattern. If you look at
gcc/configure, you'll find a line (around 26695) of comment that says:
# Test for stack protector support in target C library
And you'll see that this is the only occurrence of "stack protector" (as well
as k prot. I think we'd better use /stack protector/ as the pattern for
easy understanding.
-
a means append a line after the line that contains the pattern. (sed document)
-
gcc_cv_libc_provides_ssp=yes is the actual line being appended.