topic Re: How come my alias cannot work? in Operating System - HP-UX

How come my alias cannot work?

Rashid Ali — Wed, 22 Aug 2001 02:48:57 GMT

I worte an alias command as below,
alias psg='ps -el|grep \!*|grep -v grep'
But when I run "alias swapper", it says
grep: can't open swapper

But ps -ef|grep swapper can produce results as below,
# ps -ef|grep swapper
root 0 0 0 Apr 3 ? 1:28 swapper
root 26497 26069 2 11:51:42 ttyp3 0:00 grep swapper

Anybody know what's the reason?

Thanks,

Re: How come my alias cannot work?

Bill Hassell — Wed, 22 Aug 2001 03:13:31 GMT

The alias command is useful for holding a lot of frequently typed commands. However, alias is not like a shell script where parameters after the name of the alias can be imbedded inside the alias (ie, the name of the desired process).

However, there is a much better and more reliable alias to use:

alias psg="UNIX95= /usr/bin/ps -C"

Now type the command: psg swapper
or better yet: psg sh

You will see that only the true basename of the command is located and the non-specific matching of grep is avoided. The UNIX95 setting is documented in the ps man page.

Re: How come my alias cannot work?

linuxfan — Wed, 22 Aug 2001 03:15:08 GMT

Hi Zhang,

you could try something like this

alias psg='"ps -el|grep -v grep |grep "

once you source your .kshrc or your env file, you should be able to run
psg swapper

If you want to grep case insensitive you could modify your alias to
alias psg="ps -el |grep -v grep |grep "

Actually there is another easier way, if you are looking for a process with a known basename you could set up another alias
alias psf="UNIX95= ps -flC "

now running "psf swapper" would give you the same output.
For more information about UNIX95 (look at the manpage for ps)

-HTH
Ramesh

Re: How come my alias cannot work?

Rashid Ali — Wed, 22 Aug 2001 05:29:26 GMT

Yes, it sounds great. But I am still wondering why I can't use grep \!* and when I can use it. Because I see this example from a book "UNIX Hacks&Hints". Does the following command work on other flavours of UNIX such as Solaris or AIX?
alias psg='ps -el|grep \!*|grep -v grep'

Anybody knows how to interpret "grep \!*" and show me an example?

One more puzzle, What does it mean by "UNIX95" in your command and how does it work?

Re: How come my alias cannot work?

Sridhar Bhaskarla — Wed, 22 Aug 2001 06:34:02 GMT

Specifying the variable UNIX95 tells ps to behave like XPG4 using which we can generate desired reports like

UNIX95= ps -e -o "pcpu pid args" |sort -n

which will print percentage cpu of the processes in the reversed sorted order.

There are good explanations by Bill and other folks in this forum itself. You can try searching with UNIX95 search string.

Checkout manpage for ps to find out various options that can be used with XPG4 implementation of ps.

-Sri

PS: Please assign some points to the explanations you think are helpful to you. That will encourage people to participate more in the discussions.

Re: How come my alias cannot work?

Sridhar Bhaskarla — Wed, 22 Aug 2001 06:49:27 GMT

If you really want to use what you read in Unix hacks&hints you can do it. Only thing is there one missing grep in your alias. It should be

alias psg='ps -ef |grep \!* |grep -v grep|grep'

This is your command with an additional grep statement.

Your earlier command would be parsed as

ps -el|grep \!*|grep -v grep inetd

and obviously would result with the error message cannot open inetd.

And your grep \!* seems to get all the processes. When we specify \!, the shell will not try to match the files in the local directory.

However, as suggested by Bill and Ramesh, it is better to use XPG4 version of ps.

-Sri

Re: How come my alias cannot work?

Robin Wakefield — Wed, 22 Aug 2001 07:27:41 GMT

Hi,

alias arguments only work in csh, i.e. (note there is no = sign):

# alias pgp 'ps -ef|grep \!*|grep -v grep'
# pgp swapper
root 0 0 0 Jul 1 ? 135:39 swapper

If you want to use arguments in ksh, you have to use shell functions, or fix your alias so that any argument you type works if it is tagged onto the end of the definition, i.e.

alias pgp="ps -ef|grep -v grep | grep "

Rgds, Robin.

btw, points assignments are a little overdue ;-)