title: make: riscv64-unknown-elf-gcc: Command not found.But i have set .bashrc in /etc/profile
body: <p><a href="https://i.stack.imgur.com/uFjt7.png" rel="nofollow noreferrer">image</a></p>
  <pre><code>cgf@lzp:~/xv6-k210$ ls
  bootloader  debug  doc  fs.img  img  kernel  LICENSE  linker  Makefile  README  README_cn.md  README.md  target  tools  xv6-user
  cgf@lzp:~/xv6-k210$ sudo make fs
  riscv64-unknown-elf-gcc -Wall -Werror -O -fno-omit-frame-pointer -ggdb -g -MD -mcmodel=medany -ffreestanding -fno-common -nostdlib -mno-relax -I.    -c -o xv6-user/ulib.o xv6-user/ulib.c
  make: riscv64-unknown-elf-gcc: Command not found
  &lt;builtin&gt;: recipe for target 'xv6-user/ulib.o' failed
  make: *** [xv6-user/ulib.o] Error 127
  cgf@lzp:~/xv6-k210$ riscv64-unknown-elf-gcc
  riscv64-unknown-elf-gcc: fatal error: no input files
  compilation terminated.
  cgf@lzp:~/xv6-k210$ which riscv64-unknown-elf-gcc
  /usr/local/riscvtc/bin/riscv64-unknown-elf-gcc
  
  </code></pre>
  <p>make does`t find the command</p>
  <p>what ${PATH} is make using??</p>
  <p>which riscv64-unknown-elf-gcc can find the location of this executable file.</p>