Why are two form of expanding list using @ not providing same results?-CodePudding

In trying to answer this question, I came up with this solution, which works:

#!/bin/bash

testor=$(shopt | grep extglob | awk '{ print $2 }' )

if [ "${testor}" = "off" ]
then
    shopt -s extglob
    shopt | grep extglob
fi

ls ./WORKS/@(*.sh|*.dat|*.txt)

and the output is this:

ericthered@OasisMega1:/0__WORK$ ./junk_37.sh
extglob         on
./WORKS/abc_junk_def.txt        ./WORKS/junk_007.sh  ./WORKS/junk_28.sh
./WORKS/assignListToBashArray.sh    ./WORKS/junk_008.sh  ./WORKS/junk_28.txt
./WORKS/awkEmbeddedFunction.sh      ./WORKS/junk_009.sh  ./WORKS/junk_29.dat
./WORKS/droneConnectWiFi.sh     ./WORKS/junk_010.sh  ./WORKS/junk_29.sh
./WORKS/expandNumericDirectories.sh ./WORKS/junk_011.sh  ./WORKS/junk_30.sh
./WORKS/findMatchOnEmbeddedFilename.sh  ./WORKS/junk_012.sh  ./WORKS/junk_31.sh
./WORKS/junk_001.sh         ./WORKS/junk_013.sh  ./WORKS/musicplayer.sh
./WORKS/junk_002.sh         ./WORKS/junk_014.sh  ./WORKS/prototypeEditorWrapper.sh
./WORKS/junk_003.sh         ./WORKS/junk_015.sh  ./WORKS/prototypeSendmailWrapper.sh
./WORKS/junk_004.sh         ./WORKS/junk_26.dat  ./WORKS/reportNotLowercase.sh
./WORKS/junk_005.sh         ./WORKS/junk_26.sh
ericthered@OasisMega1:/0__WORK$

But ... if instead, I use the following line,

ls @(./WORKS/*.sh|./WORKS/*.dat|./WORKS/*.txt)

it reports this error:

ls: cannot access '@(./WORKS/*.sh|./WORKS/*.dat|./WORKS/*.txt)': No such file or directory

I would appreciate someone providing insights as to why the two forms are not equivalent.

CodePudding user response：

Converting my earlier comment to answer so that solution is easy to find for future visitors.

A pattern in extglob doesn't work with / so:

cd WORKKS

# reason of failure, presence of / in glob pattern
ls @(./junk_001.sh)
No such file or directory

# this will work fine with omission of /
ls @(junk_001.sh)
junk_001.sh

A workaround fix for your problem using extglob:

(cd WORKS; ls @(*.sh|*.dat|*.txt))

# or use find with regex
find WORKS -regextype awk -regex '.*/[^.]*\.(sh|dat|txt)$'

CodePudding user response：

As per POSIX, directory separators has to be matched explicitly in filename expansion; *, ?, [...], etc. do not match them. The following doesn't work either for the same reason.

$ ls ./WORKS[/]*.sh
ls: cannot access './WORKS[/]*.sh': No such file or directory
$ ls ./WORKS*.sh
ls: cannot access './WORKS*.sh': No such file or directory