I am trying to capture the last line of a file as a variable for use in an awk command.
Here is an example of the file (the end of it) :
cat file.txt
....
phylum:Chlorophyta 1
phylum:Mucoromycota 1
column 6:
superkingdom:Eukaryota 99
column 7:
99
I want to use that '99' as an integer in an awk command, saving it as a variable,
tail -n1 file.txt
99
e.g.
div=$(tail -n1 file.txt)
echo $div
99
To be used in a 2nd file (conf.txt), to divide the numbers in the 2nd field:
cat conf.txt
Class 88
Family 78
Genus 44
Species 23
BUT, when I try to use the $div variable in the awk command (using -v flag as suggested here and elsewhere with awk when taking a variable) I get this error:
awk -v a=$div '{print $2/a}' conf.txt
awk: can't open file {print $2/a}
source line number 1
But when saivng 99 as a variable simply on the cmd line, It works just fine:
num=99
awk -v a=$num '{print $2/a}' conf.txt
0.888889
0.787879
0.444444
0.232323
Are there extra spaces/characters in the capture from tail -1? I am missing something simple, but fundamental.
Ultimatey, I don't even want to have to save as a separate variable first If I dont have to, instead, just capture that last line number (99) and put directly into an awk cmd, e.g.:
awk '{print $2/[tail -1 file.txt]}' conf.txt
This is psuedo code (in the brackets) ...but, this would ultimately be what Id want...
Thanks for any help!
There's a space at the beginning of the last line, so the command is becoming
awk -v a= 99 '{print $2/a}' conf.txt
This is setting a to an empty string, treating 99 as the awk script, and the rest as filenames.
Remove the spaces from $div.
div=${div// /}
Use quotes as a habit in the shell.
Given:
cat file
blah blah
99
The command n=$(tail -n1 file) produces leading spaces in front of the 99:
n=$(tail -n1 file)
printf "\"%s\"\n" "$n"
" 99"
It is especially a bug that bites when you think you are checking the value of $n without quotes because the leading spaces are stripped by the shell prior to invoking echo.
Consider:
echo $n # no quotes - leading spaces stripped
99
echo "$n" # preserve whitespace...
99
Now if you try and pass that argument without quotes to awk, the space has meaning to the shell and screws up how the command is interpreted:
awk -v n=$n 'BEGIN{printf "\"%s\", %s\n", n, n+1}'
awk: fatal: cannot open file `BEGIN{printf "\"%s\", %s\n", n, n+1}' for reading: No such file or directory
vs:
awk -v n="$n" 'BEGIN{printf "\"%s\", %s\n", n, n+1}'
" 99", 100
If you want to use awk to replace the use of tail you use the idiom of FNR==NR to test if the file is the first file and $1==$1+0 to test if awk is interpreting what it sees as a number:
awk 'FNR==NR {n=$1+0==$1 ? $1+0 : n; next} # n ends up being the last number seen
$2==$2+0{print $2/n}
' file conf.txt
0.888889
0.787879
0.444444
0.232323
Rather than have shell call some command to get the last line of file.txt then save it in a shell variable, then set an awk variable to that same value populated from the shell variable and passing it to awk, just use one call to awk:
$ awk 'NR==FNR{n=$1; next} {print $2/n}' file.txt conf.txt
0.888889
0.787879
0.444444
0.232323
Enabling debug mode and running the awk command:
$ set -x
$ awk -v a=$div '{print $2/a}' conf.txt
+ awk -v a= 99 '{print $2/a}'
awk: fatal: cannot open file `{print $2/a}' for reading: No such file or directory
Of interest:
-v a= - define awk variable a as being empty
99 - awk code/script
'{print $2/a}' - first file passed to awk script, and the source of the error message
As others have pointed out you can get around the error by wrapping $div in double quotes:
$ awk -v a="$div" '{print $2/a}' conf.txt
+ awk -v 'a= 99' '{print $2/a}' conf.txt
0.888889
0.787879
0.444444
0.232323
Of interest:
-v '= 99' - define awk variable a and string ' 99'
in this case awk ignores the spaces when the rest of the variable can be interpreted as a numeric
'{print $2/a}' - awk code/script
conf.txt - file passed to awk script
Barmar and dawg have addressed stripping the blanks from div and using awk for the entire process, respectively.
Sample string:
'kernel-rt|kernel-alt|/kernel-' 'headers|xen|firmware|tools|python|utils'
cut -d' ' -f 1 string.txt gives me
'kernel-rt|kernel-alt|/kernel-'
But how do we proceed further to get just the 'kernel' from it?
Assuming you want only the 3rd kernel (in bold) and not the others
'kernel-rt|kernel-alt|/kernel-' 'headers|xen|firmware|tools|python|utils'
Here is how you extract it using single command awk (standard Linux gawk).
input="kernel-rt|kernel-alt|/kernel-' 'headers|xen|firmware|tools|python|utils"
echo $input|awk -F"|" '{split($3,a,"-");match(a[1],"[[:alnum:]]+",b);print b[0]}'
explanation
-F"|" specify field separator is | so that only is 3rd field required
split($3,a,"-") split 3rd field by -, left part assigned to a[1]
match(a[1],"[[:alnum:]]+",b) from a[1] extract sequence of alphanumeric string into b[0]
print b[0] output the matched string.
If you want to extract kernel from 2nd or 1st fields. Change $3 to $2 or $1.
$ cat file
'kernel-rt|kernel-alt|/kernel-' 'headers|xen|firmware|tools|python|utils'
$
$ awk '{print $1}' file
'kernel-rt|kernel-alt|/kernel-'
$
$ awk '{gsub(/\047/,"",$1); print $1}' file
kernel-rt|kernel-alt|/kernel-
$
$ awk '{gsub(/\047/,""); split($1,f,/[|]/); print f[1]}' file
kernel-rt
and just to make you think...
$ awk '{gsub(/\047|\.*/,"")}1' file
kernel-rt
I have a text file with the following structure:
bla1
bla2
bla3
bla4
bla5
So you can see that some lines of text are preceeded by an empty line.
I understand that sed has the concept of two buffers, a pattern space buffer and a hold space buffer, so I'm guessing these need to come in to play here, but I'm unclear how to specify them to accomplish what I need.
In my contrived example above, I'd expect to see the following lines outputted:
bla3
bla5
sed is for doing s/old/new on individual lines, that is all. Any time you start talking about buffers or doing anything related to multi-lines comparisons you're using the wrong tool.
You could do this with awk:
$ awk -v RS= -F'\n' 'NR>1{print $1}' file
bla3
bla5
but it would fail to print the first non-empty line if the first line(s) in the file were empty so this may be what you want if you want lines of all space chars considered to be empty lines:
$ awk 'NF && !p{print} {p=NF}' file
bla3
bla5
and this otherwise:
$ awk '($0!="") && (p==""){print} {p=$0}' file
bla3
bla5
All of the above will work even if there are multiple empty lines preceding any given non-empty line.
To see the difference between the 3 approaches (which you won't see given the sample input in the question):
PS1> printf '\nfoo\n \nbar\n\netc\n' | cat -E
$
foo$
$
bar$
$
etc$
PS1> printf '\nfoo\n \nbar\n\netc\n' | awk -v RS= -F'\n' 'NR>1{print $1}'
etc
PS1> printf '\nfoo\n \nbar\n\netc\n' | awk 'NF && !p{print} {p=NF}'
foo
bar
etc
PS1> printf '\nfoo\n \nbar\n\netc\n' | awk '($0!="") && (p==""){print} {p=$0}'
foo
etc
You can use the hold buffer easily to print the line before the blank like this:
sed -n -e '/^$/{x; p;}' -e h input
But I don't see an easy way to use it for your use case. For your case, instead of using the hold buffer, you could do:
sed -n -e '/^$/ba' -e d -e :a -e n -e p input
But I would do this with awk.
awk 'NR!=1{print $1}' RS= FS=\\n input-file
awk 'p;{p=/^$/}' file
above command does these for each line:
if p is 1, print line;
if line is empty, set p to 1.
if lines consisting of one or more spaces are also considered empty:
awk 'p;{p=!NF}' file
to print non-empty lines each coming right after an empty line, you can use this:
awk 'p*!(p=/^$/)' file
if p is 1 and this line is not empty (1*!(0) = 1*1 = 1), print this line;
otherwise (1*!(1) = 1*0 = 0, 0*anything = 0), don't print anything.
note that this one may not work with all awks, a portable version of this would look like:
awk 'p*(/./);{p=/^$/}' file
if lines consisting of one or more spaces are also considered empty:
awk 'p*NF;{p=!NF}' file
see them online here, and here.
If sed/awk is not mandatory, you can do it with grep:
grep -A 1 '^$' input.txt | grep -v -E '^$|--'
You can use sed to match a range of lines and do sub-matches inside the matches, like so:
# - use the "-n" option to omit printing of lines
# - match lines between a blank line (/^$/) and a non-blank one (/^./),
# then print only the line that contains at least a character,
# i.e, the non-blank line.
sed -ne '
/^$/,/^./ {
/^./{ p; }
}' input.txt
tested by gnu sed, your data in 'a':
$ sed -nE '/^$/{N;s/\n(.+)/\1/p}' a
bla3
bla5
add -i option precedes -n to real editing
I have following lines in a file. Please note I have intentionally kept the extra hash between 2 and 0 in the 2nd line.
File name : test.txt
Name#|#Age#|#Dept
AC#|#2#0#|#Science
BC#|#22#|#Commerce
I am using awk to get the data in Dept column
awk -F "#|#" -v c="Dept" 'NR==1{for (i=1; i<=NF; i++) if ($i==c){p=i; break}; next} {print $p}' "test.txt" >> result.txt
The result.txt shows me the following
|
Commerce
The first line is coming as pipe because if the extra # in the first line.
Can anyone help on this
Currently the meaning of the delimiter set is: match # or #. The pipe | character in this case acts as an OR statement; instead try using:
awk -F '#[|]#' ...
Putting | into a character class [ ... ] awk will match it literally.
If you desire to extract Dept in your content, here's a good choice you can choose from,
awk -F'#' 'NR>1{print $NF}' test.txt
output:
Science
Commerce
I have the following lines of text :
170311 005201 0433 DE(N) itemhandling itemAddBarCodeData: Barcode(1/1) <0157357069/OK> ##[ti=7672,
170311 005323 0433 DE(N) itemhandling itemAddBarCodeData: Barcode(1/1) </NOREAD> ##[ti=7672,
I have the following script :
grep "itemAddBarCodeData" %myItemHandling% | gawk -F "[<>]+" -v OFS=, "{for(i=1;i<=NF;++i){if($i~/Barcode/){print substr($1,5,2)substr($1,3,2)substr($1,1,2),substr($1,8,6),$(i+1)}}}" > %myOutputPath%%myFilename%
What I need is a script that reads only the /NOREAD and the /OK so the output is like :
11-03-17,00:52:01,NOREAD
11-03-17,00:53:23,OK
any help would be greatly appreciated
Thanks
Complex gawk approach:
awk -F"[ />]" '{patsplit($1, a, /[0-9]{2}/); patsplit($2, b, /[0-9]{2}/);
printf("%s-%s-%s,%s:%s:%s,%s\n",a[3],a[2],a[1],b[1],b[2],b[3],$10)}' inpufile
The output:
11-03-17,00:52:01,OK
11-03-17,00:53:23,NOREAD
-F"[ />]" - "composite" field separator
patsplit(string, array [, fieldpat [, steps ] ])
Divide string into pieces defined by fieldpat and store the pieces in array and
the separator strings in the seps array.
You can use this following script:
script.awk
/\/[A-Z]+>/ { match($1"-"$2,/(..)(..)(..)-(..)(..)(..)/,ts)
dt=mktime( sprintf("20%s %s %s %s %s %s",
ts[1], ts[2], ts[3],
ts[4], ts[5], ts[6]) )
dtd = strftime( "%d-%m-%y", dt )
dts = strftime( "%H:%M:%S", dt )
match ( $0, /\/[A-Z]+>/) # set RSTART and RLENGTH
print dtd, dts, substr( $0, RSTART+1, RLENGTH-2)
}
Run it like this: awk -v OFS=, -f script.awk yourfile
The important part is the second match function call, which matches
a string of capital letters [A_Z]
preceded by a /
followed by a >.
It should match the OK and NOREAD case and not the Barcode(1/1).
The variables
RSTART and
RLENGTH
are set by the match function, we have to correct them by +1 and -2, because the match RE included / and >.
The first match, mktime, strftime and the sprintf function call are another way the format the date and time. The time functions are GNU AWK extensions.
Regular awk version:
awk '
{
d=$1$2
gsub(/../,"& ",d)
split(d,T)
split($8,R,"[/>]")
printf "%s-%s-%s,%s:%s:%s,%s\n",T[3],T[2],T[1],T[4],T[5],T[6],R[2]
}
' file
With script in file:
script.awk:
{
d=$1$2
gsub(/../,"& ",d)
split(d,T)
split($8,R,"[/>]")
printf "%s-%s-%s,%s:%s:%s,%s\n",T[3],T[2],T[1],T[4],T[5],T[6],R[2]
}
awk -f script.awk file
crammed on one line..
awk '{d=$1$2; gsub(/../,"& ",d); split(d,T); split($8,R,"[/>]"); printf "%s-%s-%s,%s:%s:%s,%s\n",T[3],T[2],T[1],T[4],T[5],T[6],R[2]}' file
You don't need grep when you're using awk. With GNU awk for gensub():
$ awk '/itemAddBarCodeData/{print gensub(/(..)(..)(..) (..)(..)(..).*\/([^>]+).*/,"\\3-\\2-\\1,\\4:\\5:\\6,\\7",1)}' file
11-03-17,00:52:01,OK
11-03-17,00:53:23,NOREAD
Here's a pragmatic combination of awk and sed that is conceptually relatively simple:
On Linux and BSD/macOS:
awk -F'[ />]' -v OFS=, '/itemAddBarCodeData/ {print $1, $2, $10}' file |
sed -E 's/^(..)(..)(..),(..)(..)(..)/\3-\2-\1,\4:\5:\6/'
On a Windows system, invoked from cmd.exe, different quoting and line continuation rules apply (assumes the presence of ported GNU utilities):
awk -F"[ />]" -v OFS=, "/itemAddBarCodeData/ {print $1, $2, $10}" file ^
| sed -E "s/^(..)(..)(..),(..)(..)(..)/\3-\2-\1,\4:\5:\6/"
Note how:
"..." strings rather than '...' strings must be used to protect the embedded content from interpretation by the shell
Unlike with "..." on Unix, $ has no special meaning to cmd.exe, so it can be used as-is.
^ as the very last character on a line serves as the explicit line-continuation character, and the line must be broken before the | (whereas on Unix a line ending in | is implicitly continued).
This is only used for readability here; of course, you can place your command on a single line.