Help on variables

[Wrathchild]

Hi, I have a couple questions on using variables in scripts.
1. Can I have a command such as grep within a variable like below, or is the grep being executed as the variable is being set? If it's being executed then I can just pull it out and add it to the second line.
2. I can't figure out how to escape the date correctly; I assume it needs to be as the entire line is enclosed within the ` character

LOGCONTENTS=`grep \`date +%Y-%m-%d\` | grep -i "[n][0-9][0-9][0-9][0-9][0-9][0-9][0-9]"`
cat /tmp/logs | ${LOGCONTENTS} > /tmp/test

thanks!

 

[PHV]

Perhaps this ?
grep `date +%Y-%m-%d` /tmp/logs | grep -i 'n[0-9][0-9][0-9][0-9][0-9][0-9][0-9]' > /tmp/test

Hope This Helps, PH.
FAQ219-2884
FAQ181-2886

 

[Wrathchild]

thanks for responding PHV, however I would like to assign the commands to the variable if possible as I want to reduce redundancy in the script. If grep is being executed and the results are being stored in the variable, then I'm looking at it wrong. I was trying to "store" the entire string of commands so I can use them throughout the script. I have several occurances of grep \`date +%Y-%m-%d\` | grep -i "[n][0-9][0-9][0-9][0-9][0-9][0-9][0-9]" in my script, so I thought I'd try to store the string in a variable and only have to update it in one place in the future.

 

[PHV]

You'll nead the eval command.

Hope This Helps, PH.
FAQ219-2884
FAQ181-2886

 

[Wrathchild]

thanks PHV, I did need EVAL. Below is what I changed:

LOGCONTENTS="grep `date +%Y-%m-%d` | grep -i \"[n][0-9][0-9][0-9][0-9][0-9][0-9][0-9]\""
cat /tmp/logs | eval ${LOGCONTENTS} > /tmp/test

apparently the "ticks" or whatever you call them are telling the system to execute the commands immediately, so I was shooting myself in the foot there

 

[quirkasaurus]

LOGCONTENTS=`grep \`date +%Y-%m-%d\` | grep -i "[n][0-9][0-9][0-9][0-9][0-9][0-9][0-9]"`
cat /tmp/logs | ${LOGCONTENTS} > /tmp/test


The answer is to simplify your script like so:

date +%Y-%m-%d | read yymmdd

cat /tmp/logs |
grep $yymmdd |
grep -i "[n][0-9][0-9][0-9][0-9][0-9][0-9][0-9]" > \
/tmp/test

 

[Wrathchild]

?
that doesn't buy me anything variable-wise