UNIX for Dummies Questions & Answers

Hey, it doesn't work in Bash, either. =P I think csh is simpler. It even allows arguments, which I abuse, for aliases without needing to use a script.

What, exactly, didn't work in bash? No reason it shouldn't be possible in it -- like any proper bourne shell, it's fully recursive, hence doesn't have mysterious corners where normal expressions don't work. It's not, really -- it just looks like it. When you start doing anything more complicated than "echo line", you find places it acts weird -- as you've already found. It's also unflexible, unportable, and widely loathed for a variety of technical faults to the point its own inventor admits he "wasn't too good at programming" when he wrote it. We even have our own FAQ about it.

More to the point, you need to know how to use a proper Bourne shell. Many important things in the system use bourne and only bourne shells. Bash functions are way more powerful than aliases.

Code:

function asdf
{
    echo $1 $2 $3
}

Put that in your ~/.bashrc and 'asdf' will be a command you can use.

But it also has aliases too. Show exactly what you tried in BASH and we'll find a way to make it work.

Read this entire thread, from the beginning, and that is all I tried with both csh and bash. This is what it comes down to:

Code:

alias a="`find | egrep '.*assign[0-9]{1,2}$'`"

Its purpose is to run a C++ program without trying to run the .cpp, .o, and other files. The C++ program will either be assign# or assign##, with the # being any arbitrary number. The alias works fine when I type it in (which is a pain), so I try the .bashrc file, but then the `` end up getting executed (like it did with the .cshrc file). This means it tries to find everything everywhere that qualifies for the regular expressions.

Maybe this can be solved with a function? Things in `` are still executed in the .bashrc file, whether they're in an alias or a function...

Was that clear enough? What I posted in this entire thread has everything and could be easier to understand.

(Also, in csh, I had a problems before with a $ being in the regular expressions. The details are on the previous thread page. I tried it with bash, and it worked fine. I suppose this is one of those csh problems.)

Here is what I have, if I understood it all

Code:

~/unix.com/a$ ls
assign1       assign11      assign12.cpp  assign13.o   assign2.cpp  assign3.o
assign10      assign11.cpp  assign12.o    assign1.cpp  assign2.o
assign10.cpp  assign11.o    assign13      assign1.o    assign3
assign10.o    assign12      assign13.cpp  assign2      assign3.cpp

~/unix.com/a$ a
./assign1
./assign11
./assign12
./assign2
./assign10
./assign3
./assign13

Bash function:

Code:

a() {
    find | grep -E 'assign[[:digit:]]{1,2}$'
}

Bash Alias:

Code:

alias b='find | grep -E "assign[[:digit:]]{1,2}$"'
alias c='find | grep -E '\''assign[[:digit:]]{1,2}$'\'''

You told us bits and pieces but never your entire purpose. Being clear would have helped you a lot.

find is going to give you a relative path. Just typing your script into the shell would've shown you that. Give find $HOME to fix that.

You also need to escape your $ so the shell doesn't think it's a variable. Trivial in BASH:

Code:

alias a="`find $HOME | egrep '.*assign[0-9]{1,2}\$'`"

But you just can't make a literal $ appear inside double-quotes in CSH. It's another one of those annoying holes. You have to do something silly like

Code:

VAR1='$'
alias a="`find $HOME | egrep '.*assign[0-9]{1,2}$VAR1'`"

You should really narrow down find a lot more, too, or it's going to trawl your entire home directory, recursively, to find the one file that matches your grep regex, every time you run a shell.

tukuyomi: That finds them, yes, but I need to run them. Using `` (the backquotes) would accomplish this. However, if I use them in the .bashrc file (or in .cshrc), they are automatically run upon logging in.

Corona688: Using this in bash worked:

Code:

function a {
`find $1 | egrep '.*assign[0-9]{1,2}$'`
}

And that sparked an idea for me to make it work in csh (which is the default shell my university uses, sadly):

Code:

set var1='$'
set var0='`'
alias   a       "$var0 find \!* | egrep '.*assign[0-9]{1,2}$var1'$var0"

The \!* is not needed, but it could help with running something in a different directory.

And both ways work! Thanks for all your help, everyone. ^_^ Problem solved.

However, it makes me wonder... How might I set such variables in bash?

At last, a clue! I've been wondering for a long time just what's continuing to spread its use.