安装composer后报错proc_open(): fork failed - Cannot allocate memory
/bin/dd if=/dev/zero of=/var/swap.1 bs=1M count=1024 /sbin/mkswap /var/swap.1 /sbin/swapon /var/swap.1
/bin/dd if=/dev/zero of=/var/swap.1 bs=1M count=1024 /sbin/mkswap /var/swap.1 /sbin/swapon /var/swap.1