Solaris

You could go absolutely global if that is a requirement...
OSX 10.7.5, default bash terminal:-

Code:

#/bin/bash
# gsrc.sh
printf "/bin/echo" > /tmp/ECHO
printf "/usr/bin/printf" > /tmp/PRINTF
ECHO=`< /tmp/ECHO`
PRINTF=`< /tmp/PRINTF`
$ECHO -e "\t\tBazza...\n"
$PRINTF "\x1B[0m Walker...\n"

Results:-

Code:

Last login: Thu Sep 25 22:20:12 on ttys000
AMIGA:barrywalker~> chmod 755 gsrc.sh
AMIGA:barrywalker~> ./gsrc.sh
-e \t\tBazza...\n
x1B[0m Walker...
AMIGA:barrywalker~> printme=`< /tmp/ECHO`
AMIGA:barrywalker~> text="My name is Baz..."
AMIGA:barrywalker~> $printme "$text"
My name is Baz...
AMIGA:barrywalker~> _

HTH, good night all.

Aliases in a script?

Aliases don't work in scripts, just interactive shell sessions. Try a variable.

Code:

# defaults to 'grep' unless GREP variable is set
${GREP-grep} -q ...

Huh?

If I have a script (tester) containing:

Code:

#!/bin/ksh
alias myecho=echo
myecho $0

and make it executable using:

Code:

chmod +x tester

and execute it using:

Code:

./tester

it prints:

Code:

./tester

Aliases should work just fine in a shell script as long as the aliases being used are defined in that shell script.

The problem the OP was seeing is that aliases aren't (and, for obvious security reasons, should not be) exported.

I STRONGLY suggest that you NEVER do this!

If this convention were used by more than one script or if this script is run twice, they could wipe each other out if they ran at close to the same time. (There is a minuscule time period between when the shell wipes out the data in a file due to the redirection and the time when the printf command fills it with the name of the desired executable.) On a single processor system, this might not happen often, but on a multi-processor system, it will eventually bite you right where it hurts the most. And if there are any miscreants on your system that notice these files in /tmp, it is easy for them to replace the utilities you thought you had specified with other utilities of their choosing.

I agree the race condition risk however, it isn't easy or even possible for regular users to replace the utilities already created in /tmp. What they might do is anticipate and create hostile alternatives before the gsrc.sh script is ever executed.

That depends on what system you're using. Some systems create a per user /tmp directory (although that is not allowed by the standards); others have a single /tmp directory shared by everyone on the system. Some system administrators set up /tmp such that anyone can remove any file in that directory and create a new file with that name anytime they want; others set the permissions on that directory so that only the owner of the file or someone running "with appropriate privileges" can remove a file. The umask setting at the time the file was created will determine who can read and write that file (if they don't have permission to just remove and replace it).

On many systems, if I create /tmp/ECHO as user dwc and set the mode to 0600 and you try to run wisecracker's script that ignores any error when using printf to set the contents of that file, then the later attempt to execute

Code:

ECHO=`< /tmp/ECHO`

will fail with a permission denied error trying to read the file I created.

Utilities belong in "safe" places like /bin and $HOME/bin; not in places like /tmp.

I would go with linkage in $HOME/bin or /opt/myapp/bin.

Also, check out your code, perhaps there is a way to make in run on every os using standard toolset, therefor avoiding linking, aliases and case / if clauses per OS.

If you can paste the code, folks here might be able to clear it up a bit so it works with standard tools.

For instance :

Code:

echo "hi" | grep -q "hi" && echo "YES"

Can be replaced with something like :

Code:

echo "hi" | grep "hi" > /dev/null && echo "YES"

Regards
Peasant.