Grep for an exact match in a file

Shell Programming and Scripting
1

I am currently having some issues while trying to grep for a exact string inside a file. I have tried doing this from command line and things work fine i.e. when no match is found, return code=1 but when its done as part of my script it returns 0 for the same command - I dont know if there is an issue with the variable? Or if its because its part of a loop?

 
 grep -E '^$variable' file.csv

Above is the current code I use but have also tried others but no luck

The variable that I am using is a string that looks something like

TEST1-AA_test.csv

Any help would be appreciated.

2

Don't use single quotes (which prevent expansion by the shell), but double quotes:

grep -E "^$variable" file.csv
1 Like
3

Still having the same issue even with double quotes - Here is a copy from the log

+ TRIM_FILENAME=TEST1-AAA_test.csv
+ grep -E '^TEST1-AAA_test.csv' Valid_List.csv
+ '[' 0 = 0 ']'
+ echo -e 'TEST1-AAA_test.csv needs to be sent \n'
TEST1-AAA_test.csv needs to be sent 

 
 grep -E "^${TRIM_FILENAME}" Valid_List.csv
4

Perhaps you need to add a trailing $ to your search string. In the way that ^ at the start matches the start of line, a $ at the end matches the end of the line.

Does that help?

Your output is rather confusing in that you don't show us the code. Can we have a look?

Kind regards,
Robin

5

WHAT exactly is going wrong? I see the variable is matched and grep returns en exit code of 0 (= success).

6

Hi Rudi - The problem is that the word I am grepping for, doesnt exist in the file - It is returning 0 when it should actually return 1. From command line it works as expected, but when put into the script it returns with 0.

Below is the code that is being used - Because $TRIM_FILENAME does not exist in $Valid_List, it should not sent the file, but it is.

 
 TRIM_FILENAME=`echo $FILENAME | sed 's,_.._$DATE,,g'`
grep -E "^${TRIM_FILENAME}$" $REFERENCE/$Valid_List
         if [ $retcode = 0 ]
        then
                echo -e "$FILENAME needs to be sent "
 
                hadoop fs -cp $line $OUTPUT_DIR
                echo "successfully sent"
        else
                echo -e "$FILENAME does not need to be sent\n"
                exit 8
        fi
7

You certainly want another variable substitution, and the fix is another time double quotes: sed "s,_.._$DATE,,g"
Also it is a good idea to put double quotes around all variables, in order to allow their substitution but not additional expansions. Together with some more suggestions:

TRIM_FILENAME=`echo "$FILENAME" | sed "s,_.._$DATE,,"`
grep -E "^${TRIM_FILENAME}$" "$REFERENCE/$Valid_List"
        if [ $? -eq 0 ] # exit status of the previous command
        then
                printf "%s\n" "$FILENAME needs to be sent"
 
                hadoop fs -cp "$line" "$OUTPUT_DIR"
                echo "successfully sent"
        else
                printf "%s\n\n" "$FILENAME does not need to be sent"
                exit 8
        fi