topic Re: awk operand !~ not working? in Operating System - Linux

awk operand !~ not working?

lawrenzo_1 — Wed, 14 May 2008 08:47:06 GMT

Hello all,

I cant get the !~ operand to work - my syntax:

awk '/GIO-ES-UAM\:/ {if ($0 !~ /^\+@GIO/) print "+@GIO-ES-UAM:"}' /etc/passwd

so I am looking for the string GIO-ES-UAM in /etc/passwd and if not then print etc ...

I get no output however if I add +@GIO-ES-UAM: into /etc/passwd and run:

awk '/GIO-ES-UAM\:/ {if ($0 ~ /^\+@GIO/) print "+@GIO-ES-UAM:"}' /etc/passwd

this works?

can someone see where my mistake lies?

Thanks

Chris.

Re: awk operand !~ not working?

Rasheed Tamton — Wed, 14 May 2008 09:40:43 GMT

Hi Chris,

If I get your question correctly:

awk -F: '$0 ~ /\+@GIO-ES-UAM/ {print "+@GIO-ES-UAM:"}' passwd

Otherwise, please explain in detail.

Regards,
Rasheed Tamton.

Re: awk operand !~ not working?

lawrenzo_1 — Wed, 14 May 2008 09:52:38 GMT

ok my question is

I want to search for the string "+@GIO-ES-UAM:" in /etc/passwd - if the string does not exist in /etc/passwd I want awk to print the string.

I have used !~ (logical not) in the if statement but it wont print.

can you see where i am going wrong with my syntax?

Thanks

Re: awk operand !~ not working?

Rasheed Tamton — Wed, 14 May 2008 10:36:12 GMT

awk -F: '$0 !~ /\+@GIO-ES-UAM/ {print "+@GIO-ES-UAM:"}' passwd

But this will print the string for all the lines it gets as input from the passwd file.

Regards.
Regards.

Re: awk operand !~ not working?

lawrenzo_1 — Wed, 14 May 2008 10:37:25 GMT

I run your example

awk '$0 ~ /\+@GIO-ES-UAM/ {print "+@GIO-ES-UAM:"}' /etc/passwd

and there is no output to the command .....

I run awk '$0 !~ /\+@GIO-ES-UAM/ {print "+@GIO-ES-UAM:"}' /etc/passwd

and I get a print "+@GIO-ES-UAM:" for each line in etc passwd.

root@tstestcl.eu.unilever.com # awk '$0 !~ /\+@GIO-ES-UAM/ {print "+@GIO-ES-UAM:"}' /etc/passwd
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:
+@GIO-ES-UAM:

I want this to be displayed if there is no entry for "+@GIO-ES-UAM:" in /etc/passwd.

thanks

Re: awk operand !~ not working?

Dennis Handly — Wed, 14 May 2008 10:41:49 GMT

>I can't get the !~ operand to work - my syntax:

awk '/GIO-ES-UAM\:/ {if ($0 !~ /^\+@GIO/) print "+@GIO-ES-UAM:"}' /etc/passwd

This seems to search for "GIO-ES-UAM:". (Why are you quoting a ":"?)
Then it prints lines that don't start with "+@GIO"

>so I am looking for the string GIO-ES-UAM in /etc/passwd and if not then print etc ...

Why not pipe two greps to do the two searches?
$ grep "GIO-ES-UAM:" /etc/passwd | grep -v "+@GIO"

>I get no output however if I add +@GIO-ES-UAM: into /etc/passwd and run:
awk '/GIO-ES-UAM\:/ {if ($0 ~ /^\+@GIO/) print "+@GIO-ES-UAM:"}' /etc/passwd

This prints if you match both.

>I want to search for the string "+@GIO-ES-UAM:" in /etc/passwd - if the string does not exist in /etc/passwd I want awk to print the string.

You want to search the WHOLE file and if doesn't exist print a string? Why not just use grep?
fgrep -q "GIO-ES-UAM:" /etc/passwd
if [ $? -ne 0 ]; then
echo "+@GIO-ES-UAM:"
fi

>can you see where i am going wrong with my syntax?

We either need some more details or an example file.

>I want this to be displayed if there is no entry for "+@GIO-ES-UAM:" in /etc/passwd.

If you want this in awk, you must use flag programming. You set the flag if you find it and print it at the end:
awk '
BEGIN { found = 0 }
/GIO-ES-UAM:/ { found = 1 }
END { if (!found) print "+@GIO-ES-UAM:" }' /etc/passwd

Re: awk operand !~ not working?

Dennis Handly — Wed, 14 May 2008 10:48:37 GMT

You could optimize this and stop when you find it:
awk '
/GIO-ES-UAM:/ { exit }
END { print "+@GIO-ES-UAM:" }' /etc/passwd

Re: awk operand !~ not working?

lawrenzo_1 — Wed, 14 May 2008 10:57:00 GMT

ok i can see where your going with this ....

it doesnt work because my logic is out of sync?

I am searching for any occurance of GIO-ES-UAM in /etc/passwd with '/GIO-ES-UAM/.

if it doesnt exist I run if ($0 !~ /\^+@GIO-ES-UAM:/) print etc etc ....

as this is not logical ....

I'll use grep - and thanks

Re: awk operand !~ not working?

Dennis Handly — Wed, 14 May 2008 11:06:25 GMT

>it doesn't work because my logic is out of sync?

Basically awk (and sed) work on each line of the input file. You want something that works on all lines and then returns a status or message. You can do that with END {}.

Re: awk operand !~ not working?

James R. Ferguson — Wed, 14 May 2008 11:18:00 GMT

Hi Chris:

You are saying that you want to match the character sequence "GIO-ES-UAM:" *anywhere* in a record, *and* then using the matched record, if the *beginning* character sequence is *not* "+@GIO", then print.

So you are looking for NIS entries. I suspect that you are interested in one whose GECOS field (#5) contains "GIO-ES-UAM". If that's the case, you could specify '-F:' as the 'awk' field delimiter and match on $5 and $1:

# awk -F: '{if ($1~/\+@GIO/ && $5~/GIO-ES-UAM/) print "+@GIO-ES-UAM:"}' /etc/passwd

You said:

> I get no output however if I add +@GIO-ES-UAM: into /etc/passwd and run [my command[.

You didn't add the extra colon (which would be an extra field delimiter) did you?

Regards!

...JRF...

Re: awk operand !~ not working?

lawrenzo_1 — Wed, 14 May 2008 11:44:00 GMT

I did add a colon but didnt use -F for the delimiter.

:-

Re: awk operand !~ not working?

James R. Ferguson — Wed, 14 May 2008 11:48:36 GMT

Hi (again) Chris:

> I did add a colon but didnt use -F for the delimiter.

Well, if you are going to manually edit '/etc/passwd', you should use 'vipw' [on HP-UX, but if this is AIX there isn't one].

Too, its a good thing to run 'pwck' (or maybe 'pwdck' on AIX) if you have kludged '/etc/passwd'.

Regards!

...JRF...

Re: awk operand !~ not working?

lawrenzo_1 — Wed, 14 May 2008 11:50:22 GMT

James ...

>> You are saying that you want to match the character sequence "GIO-ES-UAM:" *anywhere* in a record, *and* then using the matched record, if the *beginning* character sequence is *not* "+@GIO", then print. <<

yes this is correct james but have worked out that by doing the it prints every line that is not matched - I think I have chosen the wrong tool for my problem so will use shell ksh syntax.

:-)

Thanks all.