linux - cd && ls | grep: How to execute a command in the current shell and pass the output -

i created alias in order not write ls every time move new directory:

alias cl='cd_(){ cd "$@" && ls; }; cd_' 

let have folder named "downloads" (which of course happen have) type following in terminal:

cl downloads 

now find myself in "downloads" folder , receive list of stuff have in folder, say: example.txt, hack.hs, picture.jpg,...

if want move directory , if there is, say, hack.hs try this:

cl downloads | grep hack 

what output:

hack.hs

but remain in folder (which means not in downloads).

i understand happens because every command executed in subshell, , cd downloads && ls executed in subshell of own , output (namely list of stuff have) gets redirected via pipe grep. why not in new folder.

my question following:

how do in order able write "cl downloads | grep hack" , "hack"-greped list of stuff , in downloads folder?

thank much, pol

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for ever googling this: quick fix proposed @gniourf_gniourf :

cl downloads > >(grep hack) 

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some marked question possible duplicate of make bash alias takes duplicates, fact bash alias takes arguments shows not case. problem @ hand how execute command in current shell while @ same time redirecting output command.

as you're aware (and covered in bashfaq #24), reason

{ cd "$@" && ls; } | grep ... 

...prevents results of cd being visible in outer shell no component of pipeline guaranteed posix run in outer shell. (some shells, including ksh [out-of-the-box] , modern bash non-default options enabled, or optionally run last piece of pipeline in parent shell, can't portably relied on).

a way avoid this, that's applicable posix shells, direct output named pipe, avoiding setting pipeline:

mkfifo mypipe grep ... <mypipe & { cd "$@" && ls; } >mypipe 

in modern ksh , bash, there's shorter syntax -- using /dev/fd entries instead of setting named pipe if operating system provides facility:

{ cd "$@" && ls; } > >(grep ...) 

in case, >(grep ...) replaced filename points either fifo or /dev/fd entry that, when written process in question, redirects output grep -- without pipeline.

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by way -- hope use of ls in manner example. output of ls not well-specified range of possible filenames, grepping innately unreliable. consider using printf '%s\0' * emit nul-delimited list of non-hidden names in directory, if want build streamed result; or using glob expressions check files matching specific pattern (bashfaq #4 covers similar scenario); extglobs available if need closer full regex matching support posix patterns support.