CODEWITHSUNDEEP
awk
didric
didric

Reputation: 3

awk string greater than variable

Being quite new to Linux and awk, this problem has me stuck. Bet it's easy to get it working. So I have this command that works fine. Printing only lines newer than a minute timestamp as text.

awk -F\" '$0> "[01/Nov/2018:15:58" {print $0}' localhost_access_log.2018-11-01.txt

The log file is formatted as follows 

[01/Nov/2018:15:53:16 +0200] x.x.x.10 "-" "-" "libwww-perl/6.13" "GET /manager/status?XML=true HTTP/1.1" 401 2473 1
[01/Nov/2018:15:53:16 +0200] x.x.x.10 "-" "-" "libwww-perl/6.13" "GET /manager/status?XML=true HTTP/1.1" 200 3070 4
[01/Nov/2018:15:58:16 +0200] x.x.x.10 "-" "-" "libwww-perl/6.13" "GET /manager/status?XML=true HTTP/1.1" 401 2473 2
[01/Nov/2018:15:58:16 +0200] x.x.x.10 "-" "-" "libwww-perl/6.13" "GET /manager/status?XML=true HTTP/1.1" 200 3070 4

But running the same command from a bash script won't work correctly. This below prints all lines from the log file. 

#!/usr/bin/bash

STAMP=$(date --date '-15 min' "+%d/%b/%Y:%H:")
MIN1=$(date --date '-15 min' "+%M")
MIN1=${MIN1:0:2}
STAMP=$STAMP$MIN1
LOGSTAMP=$(date +%Y-%m-%d)

awk -F\" '$0> "$STAMP" {print $0}' localhost_access_log.$LOGSTAMP.txt

And changing "$STAMP" -> $STAMP won't print anything.

awk -F\" '$0> $STAMP {print $0}' localhost_access_log.$LOGSTAMP.txt

Can you help?

Upvotes: 0

Views: 1645

Answers (2)

Jonathan Leffler
Jonathan Leffler

Reputation: 753665

To get the shell variable into the Awk program string, you need to terminate the single quote string before and restart it after referencing the (quoted) variable. That gets intricate:

awk -F'"' '$0> "'"$STAMP"'" {print $0}' localhost_access_log.$LOGSTAMP.txt

What awk sees as the program is then:

$0 > "01/Nov/2018:13:15" { print $0 }

Upvotes: 1

JNevill
JNevill

Reputation: 50034

Bash variables don't work in awk. You have to pass them into your awk script to an awk variable by using the -v flag:

#!/usr/bin/bash

STAMP=$(date --date '-15 min' "+%d/%b/%Y:%H:")
MIN1=$(date --date '-15 min' "+%M")
MIN1=${MIN1:0:2}
STAMP=$STAMP$MIN1
LOGSTAMP=$(date +%Y-%m-%d)

awk -F\" -v stamp="$STAMP" '$0>stamp {print $0}' localhost_access_log.$LOGSTAMP.txt

Upvotes: 3

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