put variables from shell inside ack-grep using alias

Question

I want to use ack-grep alias in .zshrc. Here is how my alias lookes like now:

alias 'ack'='ack-grep -C -i -G --match'

but what I need is to put strings from this:

% ack string1 string2

inside

alias 'ack'='ack-grep -C -i -G string1 --match string2'

How to make this?

Update

Here is the code that worked:

ack() { 
    case $# in
    1) args="$1";;
    2) args="$1 -G $2";;
    *) args="$@";;
    esac
    eval "ack-grep -iC $args"
}

In my case I need to use eval for using more than one variable.

Update 2

Updated code without security issues:

ack () {
    if (( $# == 2 )); then
        ack-grep -iC "$1" -G "$2"
    elif (( $# == 1 )); then
        ack-grep -iC "$1"
    else
        echo 'Sorry, function works only for one and two params. In other case use ack-grep. Reread .zshrc'
    fi
}

Don't use `eval` unless you absolutely have to. And in this case, you don't. — chepner, Feb 23 '13 at 00:28
It can be a security risk unless you have *absolute* control over the variables being expanded inside its argument, and it's making the shell do extra work instead of specifying exactly what you want the shell to do. — chepner, Feb 23 '13 at 15:33

score 0 · Answer 1 · answered Feb 20 '13 at 13:12

0

Use a function:

ack() { ack-grep -C -i -G $1 --match $2; }

You will probably want to make it slightly more robust. Something like:

ack() { 
    case $# in
    1) args="-G $1";;
    2) args="-G $1 --match $2";;
    *) args="$@";;
    esac
    ack-grep -C -i "$args"
}

Aliases do not provide adequate functionality for this sort of thing, and functions should almost always be used instead. (In fact, you can omit "almost" from the preceding.)

answered Feb 20 '13 at 13:12

William Pursell

204,365
48
270
300

Thanks. In my case the variation of your example worked. I've updated the post with it. – boldnik Feb 22 '13 at 13:01

chepner · Accepted Answer · 2013-02-25T13:31:07.200

0

eval is rarely necessary.

ack () { 
    if (( $# > 2 )); then
        ack-grep -iC "$@"
    else
        ack-grep -iC "$1" ${2:+-G "$2"}
    fi
}

Update: here is an exact version of your first solution, without eval.

ack() { 
    case $# in
    1) ack-grep -iC "$1";;
    2) ack-grep -iC "$1" -G "$2";;
    *) ack-grep -iC "$@";;
    esac
}

edited Feb 25 '13 at 13:31

answered Feb 23 '13 at 00:32

chepner

497,756
71
530
681

This function doesn't work because if I use `ack String` it works identical to `ack-grep -iC String`. But if you put `ack String String2` it outputs nothing, in difference to `ack-grep -iC String -G String2`. – boldnik Feb 23 '13 at 15:15
The code you posted in your update is different from the code in your original question and in William Pursell's answer (does `$1` go with `-G` or does it stand alone? Does `$2` go with `-G` or `--match`?) – chepner Feb 23 '13 at 15:38
Ok. The last version is really useful but it has restrictions. With `eval` I could use any other params if i need. But iif it can be a security issue, i'd use the updated code. – boldnik Feb 25 '13 at 09:16

put variables from shell inside ack-grep using alias

Update

Update 2

2 Answers2