stat - -format="%a" /path1/subdir
https://www.cyberciti.biz/faq/get-octal-file-permissions-from-command-line-on-linuxunix/
https://unix.stackexchange.com/questions/188674/how-to-get-file-permission-in-octal
To just see octal file permissions on a GNU/Linux:$ stat -c '%a' /etc/passwd
https://stackoverflow.com/questions/50904342/etc-passwd-vs-usr-bin-passwd
The two files are different, and serve different purpose.
/etc/passwd is user database (fun fact: contrary to its name, it doesn't store passwords - those are stored (possibly in hashed form) in /etc/shadow) - see man 5 passwd (i.e. passwd(5)), man 5 shadow (i.e. shadow(5)).
/usr/bin/passwd is utility that is supposed to modify user records stored in /etc/passwd and /etc/shadow. See man 1 passwd (i.e. passwd(1))
https://en.wikipedia.org/wiki/Filesystem_Hierarchy_Standard
https://unix.stackexchange.com/questions/5915/difference-between-bin-and-usr-bin
/sbin - Binaries needed for booting, low-level system repair, or maintenance (run level 1 or S)
/bin - Binaries needed for normal/standard system functioning at any run level.
/usr/bin - Application/distribution binaries meant to be accessed by locally logged in users
/usr/sbin - Application/distribution binaries that support or configure stuff in /sbin.
/usr/share/bin - Application/distribution binaries or scripts meant to be accesed via the web, i.e. Apache web applications
*local* - Binaries not part of a distribution; locally compiled or manually installed. There's usually never a /local/bin but always a /usr/local/bin and /usr/local/share/bin.
/bin : For binaries usable before the /usr partition is mounted. This is used for trivial binaries used in the very early boot stage or ones that you need to have available in booting single-user mode. Think of binaries like cat, ls, etc.
/sbin : Same, but for binaries with superuser (root) privileges required.
/usr/bin : Same as first, but for general system-wide binaries.
/usr/sbin : Same as above, but for binaries with superuser (root) privileges required.
sudo pam_tally2 -u 703247699 --reset
https://stackoverflow.com/questions/5163144/what-are-the-special-dollar-sign-shell-variables
$1, $2, $3, ... are the positional parameters."$@" is an array-like construct of all positional parameters, {$1, $2, $3 ...}."$*" is the IFS expansion of all positional parameters, $1 $2 $3 ....$# is the number of positional parameters.$- current options set for the shell.$$ pid of the current shell (not subshell).$_ most recent parameter (or the abs path of the command to start the current shell immediately after startup).$IFS is the (input) field separator.$? is the most recent foreground pipeline exit status.$! is the PID of the most recent background command.$0 is the name of the shell or shell script.Most of the above can be found under Special Parameters in the Bash Reference Manual. There are all the environment variables set by the shell.
For a comprehensive index, please see the Reference Manual Variable Index.