🐧 Linux errors

Linux shell, permission and package-manager errors.

Code	Error	What it means
command not found	bash: command not found	The shell can’t find an executable with that name in any directory on your PATH.
dpkg lock	E: Could not get lock /var/lib/dpkg/lock-frontend — is another process using it?	apt can’t run because another package operation (often automatic updates) holds the dpkg lock.
OOM killer	Killed / Out of memory: Killed process (Linux OOM killer)	The kernel ran out of memory and killed a process to recover — the program just prints “Killed” (exit code 13…
EACCES	Linux: Permission denied	Your user (or the service user) lacks read/write/execute permission on a file, directory or one of its parent…
SIGSEGV	Segmentation fault (core dumped)	A program accessed memory it wasn’t allowed to, and the kernel killed it with SIGSEGV (exit code 139).
EMFILE	Too many open files (EMFILE)	The process hit its file-descriptor limit — sockets, files and pipes all count.
sudoers	user is not in the sudoers file. This incident will be reported.	Your account isn’t allowed to use sudo.