capiinfo: 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/capiinfo - from package: isdn4k-utils

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

On Debian possible default full paths are:

/usr/bin/capiinfo - from package: capiutils

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

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