Hi list.
Want to read whole stdin into variable.
Don't want to spawn new processes (cat).
Don't want to reopen existing fd &0
First thing I tried: $(<&0)
It silently returns an empty string.
From bash manual:
The command substitution $(cat file) can be replaced by the equivalent but
faster $(< file).
reopening /dev/stdin mostly works, but easily broken by sudo:
# same user. works
[root@okdistr ~]# echo aaa | bash -c 'echo $(</dev/stdin)'
aaa
# different user. fail
[root@okdistr ~]# echo aaa | sudo -u nobody bash -c 'echo $(</dev/stdin)'
bash: /dev/stdin: Permission denied
# spawn new process. not want
[root@okdistr ~]# echo aaa | sudo -u nobody bash -c 'echo $(cat)'
aaa
# try to read from fd: silently fails
[root@okdistr ~]# echo aaa | sudo -u nobody bash -c 'echo $(<&0)'
# works, but too complex
[root@okdistr ~]# echo aaa | sudo -u nobody bash -c 'a=; while true; do
rc=0; read -N1024 b || rc=$?; a=$a$b; [ $rc = 0 ] || break; done; echo "$a"'
aaa
[root@okdistr ~]#
