/usr/bin/fcitx4-config is in fcitx-libs-dev 1:4.2.0-1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 | #! /bin/sh
package=fcitx
prefix=/usr
exec_prefix=/usr
includedir=/usr/include
libdir=/usr/lib/x86_64-linux-gnu
addondir=/usr/lib/x86_64-linux-gnu/fcitx
imconfigdir=/usr/share/fcitx/inputmethod
configdescdir=/usr/share/fcitx/configdesc
addonconfigdir=/usr/share/fcitx/addon
usage()
{
    cat <<EOF
Usage: fcitx4-config [OPTION]
Known values for OPTION are:
  --package             Fcitx Package Name
  --prefix              Fcitx Install Prefix
  --exec-prefix         Fcitx Binary Prefix
  --libdir              Fcitx Library Prefix
  --includedir          Fcitx Include Prefix
  --addondir            Fcitx Addon Library Dir
  --configdescdir       Fcitx Configure Description File Dir
  --addonconfigdir      Fcitx Addon Config File Dir
  --imconfigdir         Fcitx Input Method Config File Dir
  --help                display this help and exit
  --version             output version information
EOF
    exit $1
}
if test $# -eq 0; then
    usage 1
fi
cflags=false
libs=false
while test $# -gt 0; do
    case "$1" in
    -*=*) optarg=`echo "$1" | sed 's/[-_a-zA-Z0-9]*=//'` ;;
    *) optarg= ;;
    esac
    case "$1" in
    --package)
       echo $package
       ;;
    --prefix)
       echo $prefix
       ;;
    --exec-prefix)
      echo $exec_prefix
      ;;
    --includedir)
      echo $includedir
      ;;
    --libdir)
      echo $libdir
      ;;
    --addondir)
      echo $addondir
      ;;
    --configdescdir)
      echo $configdescdir
      ;;
    --addonconfigdir)
      echo $addonconfigdir
      ;;
    --imconfigdir)
      echo $imconfigdir
      ;;
    --version)
        echo 4.2.0
        exit 0
        ;;
    --help)
        usage 0
        ;;
    *)
        usage
        exit 1
        ;;
    esac
    shift
done
exit 0
 |