BASH: Assign special symbol to a variable - bash

Question

As a system Administrator I have to work on different servers with different keyboard layouts. So every time I face huge problem with finding keys like '&' ,'|'.
Is there any way I can assign these symbols to a variable and call the variable when ever I need a symbol ?
For example: Assume
echo "|" > filename
pipe = $(cat filename)
ps -ef somethinghere($(pipe)) grep java
should give me running java process. I tried everything I could but failed.
Please help.

Answer 1

The following function will do the job:
# read a number of arguments on the left-hand side; those actual arguments; then the RHS
pipe() {
local nargs
local -a firstCmd
nargs=$1; shift
firstCmd=( )
for ((i=0; i<nargs; i++)); do
firstCmd+=( "$1" ); shift
done
"${firstCmd[#]}" | "$#"
}
# basic use case
pipe 3 ps -ef somethinghere grep java
# or, for a pipeline with more than two components:
pipe 3 ps -ef somethinghere pipe 2 grep java tee log.txt
What's better is that unlike a solution using eval, it'll work even with more complicated values:
pipe 3 ps -ef 'something with spaces here' grep java
One could also write a version of this function that uses a sigil value:
pipe() {
local sigil
local -a firstCmd
sigil=$1; shift
firstCmd=( )
while (( $# )); do
if [[ $1 = "$sigil" ]]; then
shift
"${firstCmd[#]}" | pipe "$sigil" "$#"
return
else
firstCmd+=( "$1" )
shift
fi
done
"${firstCmd[#]}"
}
In this case, you could even do:
sigil=$(uuidgen) # generate a random, per-session value
pipe "$sigil" ps -ef 'something with spaces here' "$sigil" grep java "$sigil" tee log.txt

Answer 2

If you really want to do that, here is a way:
pipe="|"
eval $(echo ps -ef $pipe grep java)
with cat:
eval $(echo ps -ef $(cat pipe.txt) grep java)
Note that using eval is discouraged and that this command will become problematic as soon as you need complex commands involving quotes, escape sequences, filenames and/or arguments with spaces, etc.
In my opinion, it would be better for you to familiarise yourself with how to change keyboard layouts on different linux systems (see loadkeys for example).

Answer 3

Building on the same logic as the first solution proposed by CharlesDuffy, this should be equivalent :
pipe()
{
"${#:2:$1}" | "${#:$(($1+2))}"
}
Rather than using iteration to build an array with the first command and shift arguments until the remaining ones contain only the second command, this solution uses expansions.
"${#:2:$1}" expands $1 arguments, starting at position 2
"${#:$(($1+2))}" expands all arguments starting at position $1 + 2.
In both cases, the double quotes ensure arguments expand as one word per argument (no word splitting being performed).
If you find this too cryptic, feel free to avoid it, as readability (to the intended coder(s) who would some day have to maintain the code) is likely to trump any advantage.