Bash alias with args.

Confuseling · November 12, 2009, 2:34am

Can someone tell me why this doesn’t work in .bashrc?

alias ffind=“find / -name ‘$1’”

Cheers.

ab · November 12, 2009, 2:45am

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Because an alias is not a script that has parameters but rather a
replacement of the original text with the new text. Get rid of the $1 and
just type what you want as if ffind were everything else (which it is):

alias ffind="find / -name "
ffind something

Good luck.

Confuseling wrote:
> Can someone tell me why this doesn’t work in .bashrc?
>
> alias ffind=“find / -name ‘$1’”
>
> Cheers.
>
>
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Confuseling · November 12, 2009, 2:46am

Well, I’ve worked out that I should be using a function. I’m trying to do something like this;


function ffind() { find $1 -name '$2' 2>/dev/null ; }

But evidently it doesn’t like it…

ETA: Cross posted - but hopefully you see what I’m getting at. Surely there must be some way to do this… I just can’t figure it out.

ghostintheruins · November 12, 2009, 4:31am

Why don’t you put your script in a file, e.g. ffind.sh and make your alias in .bashrc to point to it?

I do not have experience with it, but I did a similar thing on cygwin few years ago to have X starting in an environment I like.

Good luck.

danielfortin86 · November 12, 2009, 8:20am

Speaking of problems with arguments can anyone tell me what’s wrong with this:

function overlap{
comm -1 -2 <(sort “$1”) <(sort “$2”) ;
}

Thanks,

D

ab · November 12, 2009, 9:33am

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Missing parentheses:

<code interpreter=’/bin/bash/’>
function overlap(){
comm -1 -2 <(sort “$1”) <(sort “$2”) ;
}
</code>

Good luck.

danielfortin86 wrote:
> Speaking of problems with arguments can anyone tell me what’s wrong with
> this:
>
> function overlap{
> comm -1 -2 <(sort “$1”) <(sort “$2”) ;
> }
>
> Thanks,
>
> D
>
>
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dmera · November 12, 2009, 11:34am

Hi Confuseling,
It doesn’t work because the function you are creating doesn’t accept any parameters(which is the same problem for danielfortin86):
function ffind() { find $1 -name ‘$2’ 2>/dev/null ; }

the function doesn’t know what is $1 and $2 as they were not defined in the function and the function is not accepting them.
The function should look something like this:
function ffind(param1,param2) { find $1 -name ‘$2’ 2>/dev/null ; }

now I don’t know if command find will be recognized inside the function without telling the shell that this is an outside function and depending on shell might need some type of quotes, which tells the shell that this is an outside function/executable to process it.

ken_yap · November 12, 2009, 11:58am

Incorrect. Shell functions don’t need formal parameters.

In fact the problem is that confuseling should remove the single quotes around $2 that prevent its substitution.

Just tried it and it works fine.

Confuseling · November 12, 2009, 1:56pm

Ha! You know what, I could have sworn that was one of the first things I tried…

Thanks all!

Confuseling · November 12, 2009, 2:18pm

Excuse the double post: The final product


function ffind() { find $1 -iname '*'$2'*' 2>/dev/null ; }

Great little find function. Cheers Ken.

ken_yap · November 12, 2009, 2:54pm

But you should really double quote $2 just in case it has a space in it.

Confuseling · November 12, 2009, 3:07pm

Thanks again. I’ll point out this thread, rather than copying and pasting what I’m doing there.

My Daily Rant - openSUSE Forums

It now works as I’d like it to (I think… blooming function creep :P), but any further suggestions would be most welcome.

dmera · November 13, 2009, 2:32am

Sorry for the wrong reply,Confuseling and thank you for correction ken_yap. I was not thinking straight bash scripting and thinking that a function has to have input parameters like in a lot of programming languages. I learned something today which is a plus. Again sorry for incorrect info/suggestion/comment.

Confuseling · November 13, 2009, 5:18am

No problems.

Can anyone help with my next puzzle? This one’s actually a script, rather than a .bashrc excerpt. It doesn’t behave as desired: obviously, I can fix it with case or if branches, but I’d like to know if there’s an elegant solution, forcing find to ‘evaluate’ (if that’s the word) the $POSITION variable and see it as an argument.


#!/bin/sh

optstr=clbe

CASE=-iname
LIST=
POSITION=\"*\$1*\"

while getopts $optstr var
do
  case $var in
    c) echo "case"; CASE=-name ;;
    l) echo "list"; LIST=-ls ;;
    b) echo "beginning"; POSITION=\"\$1*\" ;;
    e) echo "end"; POSITION=\"*\$1\" ;;
  esac
done
shift $(( $OPTIND - 1 )) 

echo $POSITION 
 
find ${2:-/} ${3:+-maxdepth $3} $CASE $POSITION $LIST 2>/dev/null

In order to get it to work (ish), replace $POSITION in the find line with “$1” , “$1*” or “*$1”

Also it only accepts the switches if they’re before the other arguments - but I assume that’s normal.

Any clues?

ken_yap · November 13, 2009, 6:37am

Can you give some examples of how you hope to invoke the POSITION argument?

Confuseling · November 13, 2009, 6:57am

Well, if you run it as

./ffind.sh home

for example, it would run as

POSITION = “$1”
CASE = -iname
LIST =

${2:-/} = /
${3:±maxdepth $3} =

so the final line is supposed to run as

find / -iname “$1” 2>/dev/null

which should be seen by find as

find / -iname “home” 2>/dev/null

but it doesn’t work. Find receives the string “$1” instead. If you change the last line to

find ${2:-/} ${3:±maxdepth $3} $CASE “$1” $LIST 2>/dev/null

it works. Does that make sense?

Confuseling · November 13, 2009, 7:07am

A simpler example;


#!/bin/sh

POSITION=\"*\$1*\"

echo $POSITION

find / -name $POSITION

find / -name "*$1*"

Why are the outputs of the two lines different?

ken_yap · November 13, 2009, 7:45am

Your main problem is that you are not using getopt correctly. It doesn’t work like you thought. You should look at the example provided in /usr/share/getopt/getopt-parse.bash to see how to invoke it. getopt is there to massage the command line into a standard form and to detect illegal options, not to yield the arguments one by one. That’s is done in the next step, with your own loop.

Here’s the corrected script. I have not looked too closely at possible issues with quoting and eval; that’s homework for you.

#!/bin/sh

optstr=clb:e:

CASE=-iname
LIST=
POSITION="*$1*"

# Note that we use `"$@"' to let each command-line parameter expand to a
# separate word. The quotes around `$@' are essential!
# We need TEMP as the `eval set --' would nuke the return value of getopt.
TEMP=`getopt -o $optstr -- "$@"`

if  $? != 0 ] ; then echo "Terminating..." &gt;&2 ; exit 1 ; fi

# Note the quotes around `$TEMP': they are essential!
eval set -- "$TEMP"

while true ; do
        case "$1" in
                -c) echo "case"; CASE=-name; shift ;;
                -l) echo "list"; LIST=-ls; shift ;;
                -b) echo "beginning"; POSITION="$2*"; shift 2 ;;
                -e) echo "end"; POSITION="*$2"; shift 2 ;;
                --) shift ; break ;;
                *) echo "Internal error!" ; exit 1 ;;
        esac
done

echo "$POSITION"

find ${2:-/} ${3:+-maxdepth $3} $CASE "$POSITION" $LIST 2>/dev/null

danielfortin86 · November 13, 2009, 8:31am

So I still haven’t been able to figure this problem out, this is the error that I get

compare.sh: line 2: syntax error near unexpected token <' compare.sh: line 2: function overlap{comm <(sort “$1”) <(sort “$2”) ; ’

Any ideas would be greatly appreciated!

D

Confuseling · November 13, 2009, 8:34am

Hmm… I’m using getopts, not getopt.

Don’t know how much difference that makes. I’m away for the weekend, but I’ll have a look at this later - thank you for all your help (and for the homework! :)).