tig: 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/tig - from package: tig

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

On Debian possible default full paths are:

/usr/bin/tig - from package: tig

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

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