srch_strings: command not found

Have You tried accessing the binary with the full path?

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

[root@server ~]# echo $PATH

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/srch_strings - from package: sleuthkit

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