aqhbci-tool4: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/aqhbci-tool4 - from package: aqbanking

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/aqhbci-tool4 - from package: aqbanking-tools

You may install the required package with command apt-get install {package}

Error in other languages:
aqhbci-tool4: bevel nie gevind nie
aqhbci-tool4: comandă negăsită
aqhbci-tool4: comando não encontrado
aqhbci-tool4: commande introuvable
aqhbci-tool4: command not found
aqhbci-tool4: käsku ei ole
aqhbci-tool4: không tìm thấy lệnh
aqhbci-tool4: komanda nerasta
aqhbci-tool4: Kommando nicht gefunden.
aqhbci-tool4: kommandot finns inte
aqhbci-tool4: komut yok
aqhbci-tool4: nie znaleziono polecenia
aqhbci-tool4: níor aimsíodh an t-ordú
aqhbci-tool4: no se encontró la orden
aqhbci-tool4: no s'ha trobat l'ordre
aqhbci-tool4: opdracht niet gevonden
aqhbci-tool4: parancs nem található
aqhbci-tool4: perintah tidak ditemukan
aqhbci-tool4: príkaz nenájdený
aqhbci-tool4: příkaz nenalezen
aqhbci-tool4: команда не найдена
aqhbci-tool4: командата не е открита
aqhbci-tool4: 命令找不到
aqhbci-tool4: コマンドが見つかりません