问题
We usually use a custom script to setup new FreeBSD machines after system installation, which installs tools from ports tree and sets up system environment. we also need to automate update newly installed FreeBSD-8.2 machines to FreeBSD-8.2p3 by freebsd-update. As I know, freebsd-update doesn't allow me to execute it from a shell script without a "cron" option. So I try to preload a custom program to cheat freebsd-update:
${CAT} > /tmp/isatty.c <<EOF
int isatty(const int fd) { return 1; }
EOF
${CC} -shared -fPIC -o /tmp/isatty.so /tmp/isatty.c
${ENV} LD_PRELOAD=/tmp/isatty.so LESS="-E" ${FREEBSD_UPDATE} fetch install < /dev/null
with this tweak, I can sucessfully run freebsd-update from my custom script, but after the freebsd-installer fetched files from update server, I got this error message:
Fetching metadata signature for 8.3-RELEASE from update5.FreeBSD.org... done.
Fetching metadata index... done.
Fetching 2 metadata files... gunzip: standard input is a terminal -- ignoring
metadata is corrupt.
Do I have any chance to solve this?
回答1:
You set up your LD_PRELOAD which will also be picked up by any and all processes that freebsd-update spawns. The better solution would be to create a modified version of freebsd-update that would allow you to run it from the command line without requiring user interaction.
回答2:
This utility may be what you need: empty - run processes and applications under pseudo-terminal (PTY)
This way you should be able start freebsd-update from script.
来源：https://stackoverflow.com/questions/10527207/how-to-pretend-to-be-a-tty-when-trying-to-freebsd-update-from-a-shell-script