Pipe cat/grep/arguments into variable in bash script

Question

#!/bin/bash
DATE=`date +%Y-%m-%d`
HOUR=`date +%H`
ORDERS_THIS_HOUR=`cat cli.log | grep $DATE $HOUR | grep -o "generated for Production" | wc -l`
OUTPUT="$DATE $HOUR : $ORDERS_THIS_HOUR"

echo "$OUTPUT" >> flow_productivity.log

Issue is with the second line: grep: 14: No such file or directory.

Here is a sample command, the results of which I would like to store in $ORDERS_THIS_HOUR:

cat cli.log | grep "2019-02-13 12" | grep -o "generated for Production" | wc -l

Run from the command line, the above produces the expected output.

And btw, it'll be more efficient if you get rid of the cat, and make it grep "$DATE $HOUR" <cli.log — Charles Duffy
– Charles Duffy, Commented Feb 13, 2019 at 3:21
(Not an efficiency matter, but as an aside, it's better to avoid all-caps names for your own variables: All-caps is used for variables that impact system and shell behavior, so using that namespace opens you up to collisions; see the relevant POSIX standard document at pubs.opengroup.org/onlinepubs/9699919799/basedefs/…) — Charles Duffy
– Charles Duffy, Commented Feb 13, 2019 at 3:22
...also, if the date always comes before the "generated for Production" string, you could make it something like grep -Ec "$DATE $HOUR.*generated for Production" <cli.log, collapsing the pipeline to just one command; no more FIFOs at all. — Charles Duffy
– Charles Duffy, Commented Feb 13, 2019 at 3:23
Got it everyone. Thank you -bash is like stepping through a portal into another world for me. — pcgben
– pcgben, Commented Feb 13, 2019 at 3:27

Charles Duffy · Accepted Answer · 2019-02-13 04:45:38Z

1

First -- because you aren't putting quotes around your expansions, they're passed as separate arguments to grep. The first result of string-splitting and globbing $DATE $HOUR becomes the filename that grep searches through, and subsequent ones become filenames to search.

Beyond that, it's a bad idea to call date more than once in the same script anyhow. What if your script is run as the time passes midnight? You could have the first call to date be for the end of one day, and the second one return the very beginning of the next morning. To avoid this risk, call date only once, as in the following:

now=$(date '+%Y-%m-%d %H')
msg="generated for Production"
orders_this_hour=$(grep -Ec "($now.*$msg|$msg.*$now)" <cli.log)
output="$now : $orders_this_hour"
echo "$output" >> flow_productivity.log

edited Feb 13, 2019 at 4:45

answered Feb 13, 2019 at 3:28

Charles Duffy

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deosha · Accepted Answer · 2019-02-13 03:26:20Z

1

It is taking $HOUR as filename. Make it grep "$DATE $HOUR"

edited Feb 13, 2019 at 3:26

answered Feb 13, 2019 at 3:24

deosha

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