grep and strings with spaces

[Manuales]

hi
i have:
a=`date "+%b %d"`
echo $a = "Apr 25"

if i run:
cat log | grep $a
$ cat log | grep $a
grep: can't open 25


how can i fix it ..

[Manuales]

is correct:

cat log | grep "$a"

¿?

[Steven Schweda · Accepted solution]

If it works, it's probably correct.

[Kapil Jha]

see if u doing grep $a it will be replace by
grep Apr 25
so it would search Apr and not "Apr 25"
that is why this error.
Hope u got it.
BR,
Kapil

[CharlesC]

This is how I make it work:

month=`date +%b`
day=`date +%d`
echo $month' '$day
grep "$month' '$day" syslog.log

[CharlesC]

Seems this website cannot show more than one space too. This is a re-post:

month=`date +%b`
day=`date +%d`
echo $month'BB'$day
grep "$month'BB'$day" syslog.log


Note: BB means 2 x space.

[James R. Ferguson]

Hi Manuales:

You need to quote the variable:

# grep "$a" log

...so that the shell doesn't expand the variable into "

# grep Apr 25 log

...before 'grep' sees it.

That said, do NOT spawn an extra process (the 'cat') merely to read the file and pipe it to 'grep' which is only going to read (again!) the output of the pipe. Many standard Unix utilities are written to consider the final arguments as files to be read. In fact, the error 'grep: can't open 25' in the case above, is 'grep' telling you that it can't find what it thinks is a file named "25".

Regards!

...JRF...

[Dennis Handly]

>CharlesC: cannot show more than one space too

There is a box "Retain format" you can check keep the spaces, " ".