lsp - ls, with permission numbers

2022-05-14 Greg Messer

This is a filter that simply adds the octal permissions to the beginning of each ls long-format directory entry.

Included in this project are:

• lsp.awk - the filter code
• lsp - the shell script that runs ls -l and pipes the output to lsp.awk
• findlsp - a shell script experiment that approximates the output from lsp, using the find command
• statlsp - a shell script experiment that approximates the output from lsp, using the stat command

Sample Output:

	[gmesser@gxps ~/Code/pgm-github/lsp]$ ls -l
	total 28
	-rwxr-xr-x 1 gmesser users  228 Sep 21  2015 findlsp
	-rw-r--r-- 1 gmesser users 1055 Sep 21  2015 license.txt
	-rwxr-xr-x 1 gmesser users  144 May 14 16:37 lsp
	-rwxr-xr-x 1 gmesser users 3475 May 14 15:43 lsp.awk
	-rw-r--r-- 1 gmesser users 4934 May 14 16:38 README.md
	-rwxr-xr-x 1 gmesser users  183 Sep 21  2015 statlsp
	
	[gmesser@gxps ~/Code/pgm-github/lsp]$ ls -l | awk -f lsp.awk
	total 28
	0755 -rwxr-xr-x 1 gmesser users  228 Sep 21  2015 findlsp
	0644 -rw-r--r-- 1 gmesser users 1055 Sep 21  2015 license.txt
	0755 -rwxr-xr-x 1 gmesser users  144 May 14 16:37 lsp
	0755 -rwxr-xr-x 1 gmesser users 3475 May 14 15:43 lsp.awk
	0644 -rw-r--r-- 1 gmesser users 4934 May 14 16:38 README.md
	0755 -rwxr-xr-x 1 gmesser users  183 Sep 21  2015 statlsp
	
	[gmesser@gxps ~/Code/pgm-github/lsp]$ findlsp
	755 drwxr-xr-x	gmesser	users	4096	09/21/2015 17:49 .git
	755 -rwxr-xr-x	gmesser	users	144	09/21/2015 17:49 lsp
	755 -rwxr-xr-x	gmesser	users	3475	09/21/2015 17:49 lsp.awk
	755 -rwxr-xr-x	gmesser	users	228	09/21/2015 17:49 findlsp
	644 -rw-r--r--	gmesser	users	1055	09/21/2015 17:49 license.txt
	755 -rwxr-xr-x	gmesser	users	183	09/21/2015 17:49 statlsp
	644 -rw-r--r--	gmesser	users	4934	09/21/2015 17:49 README.md
	
	[gmesser@gxps ~/Code/pgm-github/lsp]$ statlsp
	755 -rwxr-xr-x	gmesser	users	228	2015-09-21 17:49:52.332268427 -0500 ./findlsp
	644 -rw-r--r--	gmesser	users	1055	2015-09-21 17:49:52.332268427 -0500 ./license.txt
	755 -rwxr-xr-x	gmesser	users	144	2022-05-14 16:37:12.066819563 -0500 ./lsp
	755 -rwxr-xr-x	gmesser	users	3475	2022-05-14 15:43:40.303191878 -0500 ./lsp.awk
	644 -rw-r--r--	gmesser	users	4934	2022-05-14 16:38:10.888051881 -0500 ./README.md
	755 -rwxr-xr-x	gmesser	users	183	2015-09-21 17:49:52.332268427 -0500 ./statlsp

-- The lsp shell script and the lsp.awk program --

You can put lsp and lsp.awk somewhere in your path, make them executable, and use them freely. The lsp script assumes that lsp.awk is in your path. If you'd rather not put lsp.awk in your path, you will need to edit the lsp script and specify the location of lsp.awk.

The lsp script lets you enter your own options for ls. The lsp.awk program will take any ls output you want to pipe through it.

For each directory entry in the long ls output, the lsp.awk program prints the single digit for the set user ID (setuid) / set group ID (setgid) / restricted deletion (sticky bit) permission, then the three digits for the user, group and world permissions, then the rest of the original ls output. The four-digit permission number is the same as the number you would specify to the chmod command.

-- Fairly equivalent output from find and stat --

You can put findlsp and statlsp in your path if you want, but those scripts were only created to experiment with find and stat. They do the job, though.

-- Discussion --

It seems like printing the permission numbers should be an option in the ls command, but no.

My first thought was to add it myself, so I looked at the coreutils project on the gnu web site. They have a page on their site where they list rejected enhancements, along with their reasons for rejecting them. This enhancement was already rejected because find and stat could provide the octal permissions. The support from those two commands was "deemed sufficient".

I use find relatively often, and stat less so, but I did not know how to get the octal permission numbers from them. I wrote the findlsp and statlsp scripts to learn how to get that information from find and stat.

The ls command is probably the most-used command, and it is the command that most people learn first. Replicating the output from ls using find and/or stat takes a lot of effort to research. The printf-like support provided by find and stat is nice, but the format characters are an odd mix of printf and strftime formatting.

I honestly don't think find and stat provide a sufficient alternative to a simple option on the well-known ls command. Considering the odd printf-like formatting required to get the octal permission numbers from those two commands, I cannot agree about the sufficiency of the support from find or stat. It is awkward, at best.