pico: 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/pico - from package: alpine

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

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