I'm trying to write a function that looks for a last name (from user input) in the second column and returns the line to the user. Here is what I've tried (and is not working). Most importantly, when I run this with the last name in place of $input_name at the command line, it works then. As you can see, the echo to confirm that the user input was read properly. What am I missing?
60 last_search () {
61 echo "What last name are you looking for?"
62 read input_name
63 echo "$input_name"
64 awk -F':' '$2 ~ /$input_name/{print $0}' temp_phonebook
65 }
Use -v name=value to pass a shell variable to awk
Shell variable won't be expanded in single quote
print $0 is default action so take it out.
You can use:
awk -F: -v input_name="$input_name" '$2 ~ input_name' temp_phonebook
Your awk command is in single ticks, so $input_name never gets expanded.
Try something like this:
awk -F':' '$2 ~ /'"$input_name"'/{print $0}' temp_phonebook
Alternately, supply the value in advance using -v name=value:
awk -F':' -v search="${input_name}" '$2 ~ search {print $0}' temp_phonebook
okay, I figured it out! I need single quotes around the variable '$input_name'
Related
In my project, I have two files.
The content userid is :
6534
4524
4522
6635
The content userpwinfo.txt is:
nsgg315_RJ:x:4520:100::/home-gg/users/nsgg315_RJ:/bin/bash
nsgg316_ZJY:x:4521:100::/home-gg/users/nsgg316_ZJY:/bin/bash
nsgg317_CPA:x:4522:100::/home-gg/users/nsgg317_CPA:/bin/bash
nsgg318_ZRL:x:4523:100::/home-gg/users/nsgg318_ZRL:/bin/bash
nsgg319_YYM:x:4524:100::/home-gg/users/nsgg319_YYM:/bin/bash
Now I want to print the username which id is in userid. I writed a bash shell like:
for i in $(cat userid)
do
#username=`awk -F: '{if($3=="$i") print $1}' /root/userpwinfo.txt`
#username=`awk -F: '$3=="$i" {print $1}' /root/userpwinfo.txt`
#username=`awk -F: '{if($3~/$i/) print $1}' /root/userpwinfo.txt`
username=`awk -F: '{if($3==$i) print $1}' /root/userpwinfo.txt`
echo $username
done
But unlucky, it shows nothing. The correct result should be:
nsgg319_YYM
nsgg317_CPA
I have tried in command line:
awk -F: '{if($3==4524) print $1}' /root/userpwinfo.txt
It is OK
Maybe if($3==$i) is wrong in shell, Who can help me?
Your $i is the shell variable, but it's inside the quotation mark ' so awk will try to interpret it instead of the shell.
Try this:
username=`awk -F: '{if($3=='$i') print $1}' /root/userpwinfo.txt`
Note that the $i is between ' marks, meaning it's outside of the block that will be interpreted by awk, meaning it should be interpreted by the shell.
Also note that if you have an empty line in the input file, your awk command would be if($3==) which is invalid and will yield an error.
I'd like to comment also that awk is meant to have a filter and an execution block. You shouldn't need to write an if inside a block, unless you want something unusual. Meaning, your command would be more appropriately written as:
username=`awk -F: '($3=='$i'){print $1}' /root/userpwinfo.txt`
Note that even this is not a very good solution, but you already have much to think about with only these changes. When you're more familiar with awk or getting more professional, come back and check the comments. ;)
If username is what you needed using the 2 files, you could try
$ cat userpwinfo.txt
nsgg315_RJ:x:4520:100::/home-gg/users/nsgg315_RJ:/bin/bash
nsgg316_ZJY:x:4521:100::/home-gg/users/nsgg316_ZJY:/bin/bash
nsgg317_CPA:x:4522:100::/home-gg/users/nsgg317_CPA:/bin/bash
nsgg318_ZRL:x:4523:100::/home-gg/users/nsgg318_ZRL:/bin/bash
nsgg319_YYM:x:4524:100::/home-gg/users/nsgg319_YYM:/bin/bash
$ cat userid.txt
6534
4524
4522
6635
$ awk -F":" ' { if( NR==FNR ) { a[$3]=$1; next } ; if(a[$1]) print a[$1] }' userpwinfo.txt userid.txt
nsgg319_YYM
nsgg317_CPA
I have a value stored in a file named cutoff1
If I cat cutoff1 it will look like
0.34722
I want to use the value stored in cutoff1 inside an awk script. Something like following
awk '{ if ($1 >= 'cat cutoff1' print $1 }' hist1.dat >hist_oc1.dat
I think I am making some mistakes. If I do manually it will look like
awk '{ if ($1 >= 0.34722) print $1 }' hist1.dat >hist_oc1.dat
How can I use the value stored in cutoff1 file inside the above mentioned awk script?
The easiest ways to achieve this are
awk -v cutoff="$(cat cutoff1)" '($1 >= cutoff){print $1}' hist.dat
awk -v cutoff="$(< cutoff1)" '($1 >= cutoff){print $1}' hist.dat
or
awk '(NR==FNR){cutoff=$1;next}($1 >= cutoff){print $1}' cutoff1 hist.dat
or
awk '($1 >= cutoff){print $1}' cutoff="$(cat cutoff1)" hist.dat
awk '($1 >= cutoff){print $1}' cutoff="$(< cutoff1)" hist.dat
note: thanks to Glenn Jackman to point to :
man bash Command substitution: Bash performs the expansion by executing command and replacing the command substitution with the
standard output of the command, with any trailing newlines deleted.
Embedded newlines are not deleted, but they may be removed during word
splitting. The command substitution $(cat file) can be replaced by
the equivalent but faster $(< file).
since awk can read multiple files just add the filename before your data file and treat first line specially. No need for external variable declaration.
awk 'NR==1{cutoff=$1; next} $1>=cutoff{print $1}' cutoff data
PS Just noticed that it's similar to the #kvantour's second answer, but keepin it here as a different flavor.
You could use getline to read a value from another file at your convenience. First the main file to process:
$ cat > file
wait
wait
did you see that
nothing more to see here
And cutoff:
$ cat cutoff
0.34722
An wwk script that reads a line from cutoff when it meets the string see in a record:
$ awk '/see/{if((getline val < "cutoff") > 0) print val}1' file
wait
wait
0.34722
did you see that
nothing more to see here
Explained:
$ awk '
/see/ { # when string see is in the line
if((getline val < "cutoff") > 0) # read a value from cutoff if there are any available
print val # and output the value from cutoff
}1' file # output records from file
As there was only one value, it was printed only once even see was seen twice.
I have a file that has multiple lines that starts with a keyword. I only want to modify one of them and it's easy to distinguish the two. I want the one that is under the [dbinfo] section. The domain name is static so I know that won't change.
awk -F '=' '$1 ~ /^dbhost/ {print $NF};' myfile.txt
myfile.txt
[ual]
path=/web/
dbhost=ez098sf
[dbinfo]
dbhost=ec0001.us-east-1.localdomain
dbname=ez098sf_default
dbpass=XXXXXX
You can use this awk command to first check for presence of [dbinfo] section and then modify dbhost parameter:
awk -v h='newhost' 'BEGIN{FS=OFS="="}
$0 == "[dbinfo]" {sec=1} sec && $1 == "dbhost"{$2 = h; sec=0} 1' file
[ual]
path=/web/
dbhost=ez098sf
[dbinfo]
dbhost=newhost
dbname=ez098sf_default
dbpass=XXXXXX
You want to utilize a little bit of a state machine here:
awk -F '=' '
$0 ~ /^\[.*\]/ {in_db_info=($0=="[dbinfo]"}
$0 ~ /^dbhost/{if (in_db_info) print $2;}' myfile.txt
You can also do it with sed:
sed '/\[dbinfo\]/,/\[/s/\(^dbhost=\).*/\1domain.com/' myfile.txt
I am trying to pass a for loop index i into awk but keep getting unexpected token awk errors.
First I tried using the -v option within awk:
for i in "${myarray}"
awk -v var=$i '/var/{print}' myfile.dat
done
I also tried calling the variable directly using single quotes:
for i in "${myarray}"
awk '/'"$i"'/{print}' myfile.dat
done
My end goal is to learn how to pass a for loop index variable through awk as the search pattern. I'd like the above code to search through myfile.dat and print lines which contain the strings in myarray.
There are 2 problems:
Array traversing should be like this for i in "${myarray[#]}"
awk treats text between /.../ as regex literal, to use a variable use $0 ~ var.
Your code should be:
for i in "${myarray[#]}"; do
awk -v var="$i" '$0 ~ var' myfile.dat
done
{print} is default action in awk that you can omit as shown above.
you can do the same loop free as well, e.g.,
echo "${myarray[#]}" | tr ' ' '|' | awk 'NR==FNR{pat=$0; next} $0 ~ pat' - file
I have a sample file that looks like:
Sample.csv
Data_1,0,289,292,293,300,306
Data_2,0,294,3,306
Data_3,0,294,305,306
Data_4,0,294,305,306
And Im running awk on it:
scr.sh:
awk -F ',' -v tId="$1" '{for(i=3; i<NF; i++){if($i==tId) print}}' $2
By calling
./scr.sh 300 Sample.csv
That works fine and returns me exactly one row that matches.
UK_4_AB34,0,289,292,293,300,306
Original Problem statement: From the 3rd column onwards, if any of the column data matches the number given, then the line should get printed.
But if I call:
./scr.sh 306 Sample.csv
That returns me NOTHING!
I've double checked the lines in Sample.csv and confirmed that there are NO trailing spaces on any of the lines.
Any clues? Thanks.
This awk will do what you're looking for:
awk -F ',' -v tId="$1" '$0 ~ "(^|,)" tId "(,|$)"' file
Alternatively this egrep will also do the job:
egrep '(^|,)306(,|$)' file
UPDATE: Based on your comments below you can use:
awk -v tId="$1" 'BEGIN{FS=OFS=","} {p=$0; $1=$2=""} $0 ~ "(^|,)" tId "(,|$)"{print p}' file
Here is a simple solution to your problem.
Lets say your argument is stored in a variable named var
ie var=$1;
Therefore run the following command to find the occurences in your file
grep -E "^${var},|,${var},|,${var}$" yourfilename