How do I issue this linux command?

Alrick2004 · 01-17-2020, 08:56 PM

Assume that your current directory contains the files 'labtest', 'labtest1', 'labtest2', 'labtest2a', 'labtest3', and 'labtest4'.

How do I issue a command to delete only the files 'labtest1' and 'labtest2' using one ambiguous pathname. (character class)

syg00 · 01-17-2020, 08:58 PM

Sounds like homework. See the LQ rules about that.

Alrick2004 · 01-17-2020, 09:08 PM

practicing for school. But need help with this one.

rtmistler · 01-17-2020, 09:12 PM

Welcome to LQ Alrick2004,

Advice from our rules/guidelines:

Quote:

Do not post homework assignments verbatim. We're happy to assist if you have specific questions or have hit a stumbling point, however. Let us know what you've already tried and what references you have used (including class notes, books, and searches) and we'll do our best to help. Keep in mind that your instructor might also be an LQ member.

dugan · 01-17-2020, 09:35 PM

I'd use brace expansion.

Some explainers:

https://www.linuxjournal.com/content...race-expansion
https://www.gnu.org/savannah-checkou...race-Expansion
https://www.linux.com/tutorials/all-...y-braces-bash/

berndbausch · 01-17-2020, 09:55 PM

Quote:

Originally Posted by Alrick2004

Assume that your current directory contains the files 'labtest', 'labtest1', 'labtest2', 'labtest2a', 'labtest3', and 'labtest4'.

How do I issue a command to delete only the files 'labtest1' and 'labtest2' using one ambiguous pathname. (character class)

You use the rm command with an "ambiguous pathname" (a term I have never heard but which makes sense to me). The ambiguous pathname is the name of a file where some characters are expressed as character classes.

I suggest you review the concepts of filename expansion and character class from your course. These are fundamental concepts in the shell. You may also use the Bash resources in my signature.

For example, [1-4] means a character in the range of 1 to 4. labtest[1-4] means files that are named labtest1, labtest2, labtest3 or labtest4. You could call it an ambiguous pathname

Rather than a range like [1-4], you can write a character class like this: [acfgh] or [12], which means a single character out of the set (a c g g h) or the set (1 2).

BW-userx · 01-18-2020, 08:39 AM

build yourself a test bed using the examples as files by the same names, then do yourself a bash script, for easy quick editing, or command line it, changing the search patterns until your get the results you need. you can use echo in place of delete (rm) to see what you are picking out of the bunch of the files by similar names.

using a script, you can run it in the same dir as the files or give it the path to the dir to search in and run the script elsewhere.

Code:

#!/bin/bash
searchPath=

you can set the script to give you the output of what it is doing

Code:

set -xv

you can set this particular script to create the files by name for your learning purposes. this is set to have the script be ran in the same dir as the files are created in to look for the matching two filenames

Code:

#creates files by name to be tested against.
touch tabtest labtest1 labtest2 labtest2a labtest3 labtest4

you can and there are other ways to skin this cat but this is just one suggestion. put the names in an array then use that array to check against the filenames being read into the script.

Code:

#file names to be found put in an array.
patteren1=( labtest1 labtest2 )

using nested loops, (or two loops, one in a function) one to read in the files in question and another loop to check all of the files against what is in the array with the filenames in question one is looking for. using a function, because they are useful.

Code:

IsItTheOne?()
{
#using string manipulations to find matching patterns

for (( i = 0; $i < ${#patteren1[@]}; i++ ))
do  
   if [[ ${g##*/} = "${patteren1[$i]}" ]] ; then
	echo "found it $g"
   fi
done
}

Code:

for g in $(pwd)/* ; do
    IsItTheOne? $g
done

if you were to put that together in working order you might find a glitch (Bug) that needs to be worked out.

this is just to demonstrate there is more than one way to get the same results in scripting and programming.
knowing loops and string manipulations.
strings and bash

dugan · 01-18-2020, 06:43 PM

Uh, don't listen to BW-userx. All you needed was one of the following two patterns (that's the word you were looking for):

Code:

rm labtest{1,2}

Code:

rm labtest[1-2]

BW-userx · 01-18-2020, 07:05 PM

Quote:

Originally Posted by dugan

Uh, don't listen to BW-userx. All you needed was one of the following two patterns (that's the word you were looking for):

Code:

rm labtest{1,2}

Code:

rm labtest[1-2]

mine works your's prob works, and I bet there is still other ways to do this...

Quote:

this is just to demonstrate there is more than one way to get the same results in scripting and programming.

all you're doing is denying a truth, and telling someone else to do the same.