How can I use aliased commands with xargs?

Question

I have the following alias in my .aliases:

alias gi grep -i

and I want to look for foo case-insensitively in all the files that have the string bar in their name:

find -name \*bar\* | xargs gi foo

This is what I get:

xargs: gi: No such file or directory

Is there any way to use aliases in xargs, or do I have to use the full version:

   find -name \*bar\* | xargs grep -i foo

Note: This is a simple example. Besides gi I have some pretty complicated aliases that I can't expand manually so easily.

Edit: I used tcsh, so please specify if an answer is shell-specific.

Answer 1

Aliases are shell-specific - in this case, most likely bash-specific. To execute an alias, you need to execute bash, but aliases are only loaded for interactive shells (more precisely, .bashrc will only be read for an interactive shell).

bash -i runs an interactive shell (and sources .bashrc). bash -c cmd runs cmd.

Put them together: bash -ic cmd runs cmd in an interactive shell, where cmd can be a bash function/alias defined in your .bashrc.

find -name \*bar\* | xargs bash -ic gi foo

should do what you want.

Edit: I see you've tagged the question as "tcsh", so the bash-specific solution is not applicable. With tcsh, you dont need the -i, as it appears to read .tcshrc unless you give -f.

Try this:

find -name \*bar\* | xargs tcsh -c gi foo

It worked for my basic testing.

Answer 2

Turn "gi" into a script instead

eg, in /home/$USER/bin/gi:

#!/bin/sh
exec /bin/grep -i "$@"

don't forget to mark the file executable.

Answer 3

The suggestion here is to avoid xargs and use a "while read" loop instead of xargs:

find -name \*bar\* | while read file; do gi foo "$file"; done

See the accepted answer in the link above for refinements to deal with spaces or newlines in filenames.

Answer 4

This is special-character safe:

find . -print0 | xargs -0 bash -ic 'echo gi foo "$@"' --

The -print0 and -0 use \0 or NUL-terminated strings so you don't get weird things happening when filenames have spaces in them.

bash sets the first argument after the command string as $0, so we pass it a dummy argument (--) so that the first file listed by find doesn't get consumed by $0.

Answer 5

For tcsh (which does not have functions), you could use:

gi foo `find -name "*bar*"`

For bash/ksh/sh, you can create a function in the shell.

   function foobar 
   {
      gi $1 `find . -type f -name "*"$2"*"`
   }

   foobar foo bar

Remember that using backquotes in the shell is more advantageous than using xargs from multiple perspectives. Place the function in your .bashrc.

Answer 6

Using Bash you may also specify the number of args being passed to your alias (or function) like so:

alias myFuncOrAlias='echo'  # alias defined in your ~/.bashrc, ~/.profile, ...
echo arg1 arg2 | xargs -n 1 bash -cil 'myFuncOrAlias "$1"' arg0

(should work for tcsh in a similar way)

# alias definition in ~/.tcshrc
echo arg1 arg2 | xargs -n 1 tcsh -cim 'myFuncOrAlias "$1"' arg0  # untested

Answer 7

The simplest solution in you case would be to expand your alias inline. But that is valid for csh/tcsh only.

find -name \*bar\* | xargs `alias gi` foo

for bash it will be more tricky, not so handy but still might be useful:

find -name \*bar\* | xargs `alias gi | cut -d "'" -f2` foo