finding a command

Skaperen · 08-03-2022, 02:37 PM

given a command name, what is the best way to find its full path in order to be able to run that command in a situation where PATH is not set?

i originally have used the shell command "which" to quickly find this. but, recent versions of Ubuntu have merged /bin and /usr/bin such that there is one directory having all these files and references to either go to that one directory. the result is that every name is found in the first of these directories listed in PATH.

so, now, what is the best way?

kilgoretrout · 08-03-2022, 03:55 PM

On my recent *buntu and debian installations, /bin is just a symlink to /usr/bin. However, /usr/bin is listed before /bin in PATH so the which command gives the path as /usr/bin/<command>. If no PATH is set or the application is not in PATH, the simplest way I can think of to find its location is with the find command:

Code:

$ sudo find / -iname "<insert command>"

frankbell · 08-03-2022, 08:11 PM

I normally use whereis. It's specifically for finding commands.

See man whereis for more.

MadeInGermany · 08-03-2022, 10:23 PM

Set PATH and let the shell find the (short) commands.

Code:

PATH=/bin:/usr/bin:/sbin:/usr/sbin:/usr/local/bin

pan64 · 08-04-2022, 12:23 AM

which works on PATH (see man which). Otherwise you can use locate, find, whereis, you can check your installed packages, and there is a /usr/lib/command-not-found (or something similar), but in general there is no way to identify arbitrary binaries in any system.

dugan · 08-04-2022, 12:19 PM

I’d still use “which”

Skaperen · 08-04-2022, 12:56 PM

Quote:

Originally Posted by dugan

I’d still use “which”

i failed to explain well what i am looking for. i want to find the one and only "official" path of where a command is generally supposed to be found, like "ls" is supposed be at "/bin/ls".

write a script that checks all the directories listed in PATH and report all rogues and missing commands in the system it is run on, for a full set of command names or those given as arguments.

dugan · 08-04-2022, 04:55 PM

Quote:

Originally Posted by Skaperen

i failed to explain well what i am looking for. i want to find the one and only "official" path of where a command is generally supposed to be found, like "ls" is supposed be at "/bin/ls".

How are you defining that?

boughtonp · 08-04-2022, 05:13 PM

Quote:

Originally Posted by Skaperen

i want to find the one and only "official" path of where a command is generally supposed to be found, like "ls" is supposed be at "/bin/ls".

The question you need to ask is: Who says "ls" is supposed to be there?

The answer is the Filesystem Hierarchy Standard, which defines what must/may go in "/bin" and "/sbin" (and thus their /usr counterparts).

I don't know if anyone has encoded that information into a script, but it wouldn't be difficult to do.

dugan · 08-04-2022, 07:29 PM

Quote:

Originally Posted by dugan

How are you defining that?

Look. I've had people miss the point when I try to make them think like this, so I'll spell it out. There's no such thing.

chrism01 · 08-05-2022, 12:24 AM

Also, define "rogues and missing commands "...

Just because a cmd doesn't exist on a system, it doesn't necessarily mean it should be there. Systems vary enormously...

If your distro is RPM based, the rpm -V (plus more options) can check verify installed pkgs against what the rpmdb says it should be.
See also https://www.cyberciti.biz/tips/reset...ermission.html to fix various errors.

dugan · 08-05-2022, 10:40 AM

I think this is what you’re actually looking for

https://www.sandflysecurity.com/blog...ile-poisoning/

Skaperen · 08-05-2022, 06:05 PM

Quote:

Originally Posted by dugan

Look. I've had people miss the point when I try to make them think like this, so I'll spell it out. There's no such thing.

no such thing as what? if you are referring to my use of "official", then pay attention to my use of quotes.

Skaperen · 08-05-2022, 06:16 PM

Quote:

Originally Posted by chrism01

Also, define "rogues and missing commands "...

Just because a cmd doesn't exist on a system, it doesn't necessarily mean it should be there. Systems vary enormously...

rogues are commands that are there but not what you expect them to be.

missing are commands you expected to be there but are not there.

that systems vary enormously is all the more reason to write such a script.

Quote:

Originally Posted by chrism01

If your distro is RPM based, the rpm -V (plus more options) can check verify installed pkgs against what the rpmdb says it should be.
See also https://www.cyberciti.biz/tips/reset...ermission.html to fix various errors.

i'll skip this, for now. i no longer have any RPM based distros. when i get a current project ready to deploy on AWS, i might have quite a few. for now, i'm running Xubuntu 20.04.

Skaperen · 08-05-2022, 06:21 PM

Quote:

Originally Posted by boughtonp

The question you need to ask is: Who says "ls" is supposed to be there?

The answer is the Filesystem Hierarchy Standard, which defines what must/may go in "/bin" and "/sbin" (and thus their /usr counterparts).

I don't know if anyone has encoded that information into a script, but it wouldn't be difficult to do.

i don't know, either. if someone has, i'm sure someone else will chastise me about it while being careful to not say where it is.