Sometimes I want a bash script that's mostly a help file. There are probably better ways to do things, but sometimes I want to just have a file called "awk_help" that I run, and it dumps my awk notes to the terminal.
How can I do this easily?
Another idea, use #!/bin/cat -- this will literally answer the title of your question since the shebang line will be displayed as well.
Turns out it can be done as pretty much a one liner, thanks to #CharlesDuffy for the suggestions!
Just put the following at the top of the file, and you're done
cat "$BASH_SOURCE" | grep -v EZREMOVEHEADER
So for my awk_help example, it'd be:
cat "$BASH_SOURCE" | grep -v EZREMOVEHEADER
# Basic form of all awk commands
awk search pattern { program actions }
# advanced awk
awk 'BEGIN {init} search1 {actions} search2 {actions} END { final actions }' file
# awk boolean example for matching "(me OR you) OR (john AND ! doe)"
awk '( /me|you/ ) || (/john/ && ! /doe/ )' /path/to/file
# awk - print # of lines in file
awk 'END {print NR,"coins"}' coins.txt
# Sum up gold ounces in column 2, and find out value at $425/ounce
awk '/gold/ {ounces += $2} END {print "value = $" 425*ounces}' coins.txt
# Print the last column of each line in a file, using a comma (instead of space) as a field separator:
awk -F ',' '{print $NF}' filename
# Sum the values in the first column and pretty-print the values and then the total:
awk '{s+=$1; print $1} END {print "--------"; print s}' filename
# functions available
length($0) > 72, toupper,tolower
# count the # of times the word PASSED shows up in the file /tmp/out
cat /tmp/out | awk 'BEGIN {X=0} /PASSED/{X+=1; print $1 X}'
# awk regex operators
https://www.gnu.org/software/gawk/manual/html_node/Regexp-Operators.html
I found another solution that works on Mac/Linux and works exactly as one would hope.
Just use the following as your "shebang" line, and it'll output everything from line 2 on down:
test.sh
#!/usr/bin/tail -n+2
hi there
how are you
Running this gives you what you'd expect:
$ ./test.sh
hi there
how are you
and another possible solution - just use less, and that way your file will open in searchable gui
#!/usr/bin/less
and this way you can grep if for something too, e.g.
$ ./test.sh | grep something
Related
I have spent hours trying to solve this. There are a bunch of answers as to how to prepend to all lines or specific lines but not with a variable text and a variable number.
while [ $FirstVariable -lt $NextVariable ]; do
#sed -i "$FirstVariables/.*/$FirstVariableText/" "$PWD/Inprocess/$InprocessFile"
cat "$PWD/Inprocess/$InprocessFile" | awk 'NR==${FirstVariable}{print "$FirstVariableText"}1' > "$PWD/Inprocess/Temp$InprocessFile"
FirstVariable=$[$FirstVariable+1]
done
Essentially I am looking for a particular string delimiter and then figuring out where the next one is and appending the first result back into the following lines... Note that I already figured out the logic I am just having issues prepending the line with the variables.
Example:
This >
Line1:
1
2
3
Line2:
1
2
3
Would turn into >
Line1:
Line1:1
Line1:2
Line1:3
Line2:
Line2:1
Line2:2
Line2:3
You can do all that using below awk one liner.
Assuming your pattern starts with Line, then the below script can be used.
> awk '{if ($1 ~ /Line/ ){var=$1;print $0;}else{ if ($1 !="")print var $1}}' $PWD/Inprocess/$InprocessFile
Line1:
Line1:1
Line1:2
Line1:3
Line2:
Line2:1
Line2:2
Line2:3
Here is how the above script works:
If the first record contains word Line then it is copied into an awk variable var. From next word onwards, if the record is not empty, the newly created var is appended to that record and prints it producing the desired result.
If you need to pass the variables dynamically from shell to awk you can use -v option. Like below:
awk -v var1=$FirstVariable -v var2=$FirstVariableText 'NR==var{print var2}1' > "$PWD/Inprocess/Temp$InprocessFile"
The way you addressed the problem is by parsing everything both with bash and awk to process the file. You make use of bash to extract a line, and then use awk to manipulate this one line. The whole thing can actually be done with a single awk script:
awk '/^Line/{str=$1; print; next}{print (NF ? str $0 : "")}' inputfile > outputfile
or
awk 'BEGIN{RS="";ORS="\n\n";FS=OFS="\n"}{gsub(FS,OFS $1)}1' inputfile > outputfile
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.
Hi I have a shell command like this.
s3=$(awk 'BEGIN{ print "S3 bucket path" }
/Executing command\(queryId/{ sub(/.*queryId=[^[:space:]]+: /,""); q=$0 }
/s3:\/\//{ print "," $10 }' OFS=',' hive-server2.log)
The output of the above command like this.
echo $s3
2018-02-21T17:58:22,
2018-02-21T17:58:26,
2018-02-21T18:05:33,
2018-02-21T18:05:34
I want to select the last line only. I need the last output like this.
2018-02-21T18:05:34
I tried like this.
awk -v $s3 '{print $(NF)}'
Not working.Any help will be appreciated.
In general, command | tail -n 1 prints the last line of the output from command. However, where command is of the form awk '... { ... print something }' you can refactor to awk '... { ... result = something } END { print result }' to avoid spawning a separate process just to discard the other output. (Conversely, you can replace awk '/condition/ { print something }' | head -n 1 with awk '/condition/ { print something; exit }'.)
If you already have the result in a shell variable s3 and want to print just the last line, a parameter expansion echo "${s3##*$'\n'}" does that. The C-style string $'\n' to represent a newline is a Bash extension, and the parameter expansion operator ## to remove the longest matching prefix isn't entirely portable either, so you should make sure the shebang line says #!/bin/bash, not #!/bin/sh
Notice also that $s3 without quotes is an error unless you specifically require the shell to perform whitespace tokenization and wildcard expansion on the value. You should basically always use double quotes around variables except in a couple of very specific scenarios.
Your Awk command would not work for two reasons; firstly, as explained in the previous paragraph, you are setting s3 to the first token of the variable, and the second is your Awk script (probably a syntax error). In more detail, you are basically running
awk -v s3=firstvalue secondvalue thirdvalue '{ print $(NF) }'
^ value ^ script to run ^ names of files ...
where you probably wanted to say
awk -v s3=$'firstvalue\nsecondvalue\nthirdvalue' '{ print $(NF) }'
But even with quoting, your script would set v to something but then tell Awk to (ignore the variable and) process standard input, which on the command line leaves it reading from your terminal. A fixed script might look like
awk 'END { print }' <<<"$s3"
which passes the variable as standard input to Awk, which prints the last line. The <<<value "here string" syntax is also a Bash extension, and not portable to POSIX sh.
much simple way is
command | grep "your filter" | tail -n 1
or directly
command | tail -n 1
You could try this:
echo -e "This is the first line \nThis is the second line" | awk 'END{print}'
another approach can be, processing the file from the end and exiting after first match.
tac file | awk '/match/{print; exit}'
Hi you can do it just by adding echo $s3 | sed '$!d'
s3=$(awk 'BEGIN{ print "S3 bucket path" }/Executing command\(queryId/{ sub(/.*queryId=[^[:space:]]+: /,""); q=$0 } /s3:\/\//{ print "," $10 }' OFS=',' hive-server2.log)
echo $s3 | sed '$!d'
It will simply print:-
2018-02-21T18:05:34
Hope this will help you.
I put together this shell script to do two things:
Change the delimiters in a data file ('::' to ',' in this case)
Select the columns and I want and append them to a new file
It works but I want a better way to do this. I specifically want to find an alternative method for exploding each line into an array. Using command line arguments doesn't seem like the way to go. ANY COMMENTS ARE WELCOME.
# Takes :: separated file as 1st parameters
SOURCE=$1
# create csv target file
TARGET=${SOURCE/dat/csv}
touch $TARGET
echo #userId,itemId > $TARGET
IFS=","
while read LINE
do
# Replaces all matches of :: with a ,
CSV_LINE=${LINE//::/,}
set -- $CSV_LINE
echo "$1,$2" >> $TARGET
done < $SOURCE
Instead of set, you can use an array:
arr=($CSV_LINE)
echo "${arr[0]},${arr[1]}"
The following would print columns 1 and 2 from infile.dat. Replace with
a comma-separated list of the numbered columns you do want.
awk 'BEGIN { IFS='::'; OFS=","; } { print $1, $2 }' infile.dat > infile.csv
Perl probably has a 1 liner to do it.
Awk can probably do it easily too.
My first reaction is a combination of awk and sed:
Sed to convert the delimiters
Awk to process specific columns
cat inputfile | sed -e 's/::/,/g' | awk -F, '{print $1, $2}'
# Or to avoid a UUOC award (and prolong the life of your keyboard by 3 characters
sed -e 's/::/,/g' inputfile | awk -F, '{print $1, $2}'
awk is indeed the right tool for the job here, it's a simple one-liner.
$ cat test.in
a::b::c
d::e::f
g::h::i
$ awk -F:: -v OFS=, '{$1=$1;print;print $2,$3 >> "altfile"}' test.in
a,b,c
d,e,f
g,h,i
$ cat altfile
b,c
e,f
h,i
$
I have the following file:
test
1
My
2
Hi
3
i need a way to use cat ,grep or awk to give the following output:
test1
My2
Hi3
How can i achieve this in a single command? something like
cat file.txt | grep ... | awk ...
Note that its always a string followed by a number in the original text file.
sed 'N;s/\n//' file.txt
This should give the desired output when the content is in file.txt
paste -d "" - - < filename
This takes consecutive lines and pastes them together delimited by the empty string.
awk '{printf("%s", $0);} !(NR%2){printf("\n");}' file.txt
EDIT: I just noticed that your question requires the use of cat and grep. Both of those programs are unnecessary to achieve your stated aims. If you have some reason for including them that you haven't mentioned, try this (uselessly inefficient) version of the line I wrote immediately above:
cat file.txt | grep '^' | awk '{printf("%s", $0);} !(NR%2){printf("\n");}'
It is possible that this command uses features not present in the original awk program. You may need to invoke the new awk program, nawk instead.
If your input file is always 1 number then 1 string, and you only want the strings, all you have to do is take every other line.
If you only want the odd lines, you can do awk 'NR % 2' file.txt
If you want the evens, this becomes awk 'NR % 2==0' data
Here is the answer:
cat file.txt | awk 'BEGIN { lno = 0 } { val=$0; if (lno % 2 == 1) {printf "%s\n", $0} else {printf "%s", $0}; ++lno}'