samtools_0.1.18: 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 Debian possible default full paths are:

/usr/bin/samtools_0.1.18 - from package: tophat

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

Error in other languages:
samtools_0.1.18: bevel nie gevind nie
samtools_0.1.18: comandă negăsită
samtools_0.1.18: comando não encontrado
samtools_0.1.18: commande introuvable
samtools_0.1.18: command not found
samtools_0.1.18: käsku ei ole
samtools_0.1.18: không tìm thấy lệnh
samtools_0.1.18: komanda nerasta
samtools_0.1.18: Kommando nicht gefunden.
samtools_0.1.18: kommandot finns inte
samtools_0.1.18: komut yok
samtools_0.1.18: nie znaleziono polecenia
samtools_0.1.18: níor aimsíodh an t-ordú
samtools_0.1.18: no se encontró la orden
samtools_0.1.18: no s'ha trobat l'ordre
samtools_0.1.18: opdracht niet gevonden
samtools_0.1.18: parancs nem található
samtools_0.1.18: perintah tidak ditemukan
samtools_0.1.18: príkaz nenájdený
samtools_0.1.18: příkaz nenalezen
samtools_0.1.18: команда не найдена
samtools_0.1.18: командата не е открита
samtools_0.1.18: 命令找不到
samtools_0.1.18: コマンドが見つかりません