topic Re: If sentence .. in Operating System - Linux

If sentence ..

Manuales — Wed, 14 Dec 2005 10:57:43 GMT

hi ..
how cay i use if to indicate a sentence:
if $a (is bigger than) $b
then ...

"is bigger than" how can i indicate it in if sentence? is like -ge? is like -aq? what is, i don't remember it ...!!!

Thanks, Manuales.

Re: If sentence ..

Geoff Wild — Wed, 14 Dec 2005 11:00:33 GMT

if (( $a > $b ))

Rgds...Geoff

Re: If sentence ..

Slawomir Gora — Wed, 14 Dec 2005 11:02:00 GMT

if [ $a -gt $b ]
then
...
fi

Re: If sentence ..

Peter Godron — Wed, 14 Dec 2005 11:02:34 GMT

Manuales,
if you type man test it will show some useful syntax.

Re: If sentence ..

Manuales — Wed, 14 Dec 2005 11:02:59 GMT

thanks, buy if you use "test"

if test $a ...... Bb

whad do you put in space "...." ?

Tnanks, Manuales.

Re: If sentence ..

Oviwan — Wed, 14 Dec 2005 11:04:49 GMT

ksh:

for strings:
"=" equal
"!=" not equal

for numbers:
"-eq" equal
"-ne" not equal
"-gt" greater than
"-lt" less than

Regards

Re: If sentence ..

James R. Ferguson — Wed, 14 Dec 2005 11:07:57 GMT

Hi Manuales:

I assume that you want the Posix (or 'ksh') shell syntax.

If so, see the man pages for 'test' and the man pages for 'sh-posix'.

Regards!

...JRF...

Re: If sentence ..

Peter Godron — Wed, 14 Dec 2005 11:10:43 GMT

Manuales,

#!/usr/bin/ksh
a="A"
b="B"
if [[ "$a" > "$b" ]]
then
echo a greater than b
else
echo a not greater than b
fi

Re: If sentence ..

Rodney Hills — Wed, 14 Dec 2005 11:14:34 GMT

The "test" command and its equivalent "[ ... ]" syntax are different then the "[[ ... ]]" syntax used in "ksh".

A review of "man test" and "man ksh" will explain the differences.

For instance-
if [ ab = a* ]... is false since it is a string compare, whereas
if [[ ab = a* ]]... is true since it is doing a pattern match.

read the "man" pages for the details...

Rod Hills

Re: If sentence ..

Manuales — Wed, 14 Dec 2005 14:03:28 GMT

i'm using csh
why do i have next error?
serverunix:girl1 279> prueba.csh
if: Expression syntax.

my script is:
if ($bb = 1)
then
echo "hola"
else
echo "adios"
eif

why is the problem??

Thanks, Manuales.

Re: If sentence ..

Oviwan — Wed, 14 Dec 2005 14:15:57 GMT

try this:

if ($bb = 1) then
echo "hola"
else
echo "adios"
endif

Re: If sentence ..

Patrick Wallek — Wed, 14 Dec 2005 14:17:19 GMT

CSH is a completely different beast from sh or ksh.

Your script should be:

if ( $bb == 1 ) then
echo "hola"
else
echo "adios"
endif

Note the differences.

1st line -- You needs space between the open and close parentheses and the expressions. Also you needed a '==' (2 equal signs together) and the 'then' needs to be on the first line.

The last line of the script has to be 'endif'.

# man csh

will give you a LOT of info on the C-shell.

Re: If sentence ..

Manuales — Wed, 14 Dec 2005 14:28:15 GMT

Thanks Patrick !!

i've worked with ksh ..

do you know if with csh you can make functiions llike ksh? it means, with ksh there is a variable specially to redirect a path where there will be functions .. do you kwno if this exists to csh?

Thanks, Manuales.

Re: If sentence ..

James R. Ferguson — Wed, 14 Dec 2005 14:35:31 GMT

Hi Manuales:

The 'csh' shell is far inferior to the Posix ('usr/bin/sh'), 'ksh', and 'bash' shells.

See here, for one discussion of why *not* to use 'csh':

http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/

Beyond, that, on HP-UX, for the 'root' account, in '/etc/passwd', NEVER specify any shell other than '/sbin/sh'. To do so will render your server unusable.

The Posix shell lives in '/sbin/sh' as a staticly-linked binary. As such, everything it needs to run is available in single-user mode (when '/usr' isn't mounted). The Posix shell in '/usr/bin/sh' is for general users and uses dynamically linked libraries in '/usr'. Non-root users should specify this shell in preference to '/sbin/sh'.

Regards!

...JRF...

Re: If sentence ..

Patrick Wallek — Wed, 14 Dec 2005 14:47:37 GMT

I don't know that much about csh. I would advise you to read the man page if you must use csh.

I try to avoid it if at all possible. I much prefer the POSIX shell.

Re: If sentence ..

Manuales — Wed, 14 Dec 2005 16:15:50 GMT

Hi !!
i have a problem,
running script manually is ok. but if i run it from cron i have an error:

/home/scripts/test.sh[21]: Syntax error at line 56 : `else' is
not matched.
why?

my script is:

#!/usr/bin/csh
set p_monit=/home/scripts/MONITORING
#--->12132005 This is to take correct name in script
cd /interface/Towers/exe/backup
set aa=`ls -l | grep earn | awk '{ print $NF }'`
set bb=`echo $aa | wc -w`
if ($bb == 1) then
mv $aa db.opo
chmod 775 db.opo
else
set mensaje=`cat $p_monit/mail_messages.txt | grep 01 | cut -d":" -f2`
echo $mensaje | mailx -s "01 ORANGE ALERT to Mexico" me@patito.com.mx
endif

Thanks, Manuales.

Re: If sentence ..

James R. Ferguson — Wed, 14 Dec 2005 16:27:20 GMT

Hi Manuales:

The 'cron' environment is quite sparse, containing:

HOME=user's-home-directory
LOGNAME=user's-login-id
PATH=/usr/bin:/usr/sbin:.
SHELL=/usr/bin/sh

That is, *any* variables that are usually in your profile or login file are *not* available unless you specifically include them.

Regards!

...JRF...

Re: If sentence ..

Manuales — Wed, 14 Dec 2005 16:31:59 GMT

but problem is with if sentence, now i have this problem:

/home/scripts/test.sh[21]: Syntax error at line 21 : `if' is not matched

Thanks, Manuales.

Re: If sentence ..

Oviwan — Wed, 14 Dec 2005 16:32:14 GMT

Hi,

put su - user before the script in your crontab

Regards

Re: If sentence ..

Oviwan — Wed, 14 Dec 2005 16:34:24 GMT

Hi,

put su - USERNAME in front the script in your crontab

Regards