Hi I have something like this in my bash script
gawk '{ printf "%s %s", $1, $2 }' test.txt
Normaly I can limit the lenght of the strings with a number before the s like this:
# Limit strings to 10 characters
gawk '{ printf "%10s %10s", $1, $2 }' test.txt
How I can use a var for that limit ? I get the width of the current terminal with tput cols and I want to set dinamically the lenght of the strings.
You can use * in the format specifier to get the width from an argument to printf:
$ gawk -v width=10 '{ printf "%*s %*s\n", width, $1, width, $2 }' <<<"a b"
a b
$ gawk -v width=3 '{ printf "%*s %*s\n", width, $1, width, $2 }' <<<"a b"
a b
This also works with the precision argument (The number after a . in the format).
One way is to break up your format string and insert the variable.
awk -v w=10 '{printf "%."w"f %."w"f", $1, $2}' <<< '1.2 3.5'
1.2000000000 3.5000000000
awk -v w=3 '{printf "%."w"f %."w"f", $1, $2}' <<< '1.2 3.5'
1.200 3.500
Related
I found some ways to pass external shell variables to an awk script, but I'm confused about ' and ".
First, I tried with a shell script:
$ v=123test
$ echo $v
123test
$ echo "$v"
123test
Then tried awk:
$ awk 'BEGIN{print "'$v'"}'
$ 123test
$ awk 'BEGIN{print '"$v"'}'
$ 123
Why is the difference?
Lastly I tried this:
$ awk 'BEGIN{print " '$v' "}'
$ 123test
$ awk 'BEGIN{print ' "$v" '}'
awk: cmd. line:1: BEGIN{print
awk: cmd. line:1: ^ unexpected newline or end of string
I'm confused about this.
#Getting shell variables into awk
may be done in several ways. Some are better than others. This should cover most of them. If you have a comment, please leave below. v1.5
Using -v (The best way, most portable)
Use the -v option: (P.S. use a space after -v or it will be less portable. E.g., awk -v var= not awk -vvar=)
variable="line one\nline two"
awk -v var="$variable" 'BEGIN {print var}'
line one
line two
This should be compatible with most awk, and the variable is available in the BEGIN block as well:
If you have multiple variables:
awk -v a="$var1" -v b="$var2" 'BEGIN {print a,b}'
Warning. As Ed Morton writes, escape sequences will be interpreted so \t becomes a real tab and not \t if that is what you search for. Can be solved by using ENVIRON[] or access it via ARGV[]
PS If you have vertical bar or other regexp meta characters as separator like |?( etc, they must be double escaped. Example 3 vertical bars ||| becomes -F'\\|\\|\\|'. You can also use -F"[|][|][|]".
Example on getting data from a program/function inn to awk (here date is used)
awk -v time="$(date +"%F %H:%M" -d '-1 minute')" 'BEGIN {print time}'
Example of testing the contents of a shell variable as a regexp:
awk -v var="$variable" '$0 ~ var{print "found it"}'
Variable after code block
Here we get the variable after the awk code. This will work fine as long as you do not need the variable in the BEGIN block:
variable="line one\nline two"
echo "input data" | awk '{print var}' var="${variable}"
or
awk '{print var}' var="${variable}" file
Adding multiple variables:
awk '{print a,b,$0}' a="$var1" b="$var2" file
In this way we can also set different Field Separator FS for each file.
awk 'some code' FS=',' file1.txt FS=';' file2.ext
Variable after the code block will not work for the BEGIN block:
echo "input data" | awk 'BEGIN {print var}' var="${variable}"
Here-string
Variable can also be added to awk using a here-string from shells that support them (including Bash):
awk '{print $0}' <<< "$variable"
test
This is the same as:
printf '%s' "$variable" | awk '{print $0}'
P.S. this treats the variable as a file input.
ENVIRON input
As TrueY writes, you can use the ENVIRON to print Environment Variables.
Setting a variable before running AWK, you can print it out like this:
X=MyVar
awk 'BEGIN{print ENVIRON["X"],ENVIRON["SHELL"]}'
MyVar /bin/bash
ARGV input
As Steven Penny writes, you can use ARGV to get the data into awk:
v="my data"
awk 'BEGIN {print ARGV[1]}' "$v"
my data
To get the data into the code itself, not just the BEGIN:
v="my data"
echo "test" | awk 'BEGIN{var=ARGV[1];ARGV[1]=""} {print var, $0}' "$v"
my data test
Variable within the code: USE WITH CAUTION
You can use a variable within the awk code, but it's messy and hard to read, and as Charles Duffy points out, this version may also be a victim of code injection. If someone adds bad stuff to the variable, it will be executed as part of the awk code.
This works by extracting the variable within the code, so it becomes a part of it.
If you want to make an awk that changes dynamically with use of variables, you can do it this way, but DO NOT use it for normal variables.
variable="line one\nline two"
awk 'BEGIN {print "'"$variable"'"}'
line one
line two
Here is an example of code injection:
variable='line one\nline two" ; for (i=1;i<=1000;++i) print i"'
awk 'BEGIN {print "'"$variable"'"}'
line one
line two
1
2
3
.
.
1000
You can add lots of commands to awk this way. Even make it crash with non valid commands.
One valid use of this approach, though, is when you want to pass a symbol to awk to be applied to some input, e.g. a simple calculator:
$ calc() { awk -v x="$1" -v z="$3" 'BEGIN{ print x '"$2"' z }'; }
$ calc 2.7 '+' 3.4
6.1
$ calc 2.7 '*' 3.4
9.18
There is no way to do that using an awk variable populated with the value of a shell variable, you NEED the shell variable to expand to become part of the text of the awk script before awk interprets it. (see comment below by Ed M.)
Extra info:
Use of double quote
It's always good to double quote variable "$variable"
If not, multiple lines will be added as a long single line.
Example:
var="Line one
This is line two"
echo $var
Line one This is line two
echo "$var"
Line one
This is line two
Other errors you can get without double quote:
variable="line one\nline two"
awk -v var=$variable 'BEGIN {print var}'
awk: cmd. line:1: one\nline
awk: cmd. line:1: ^ backslash not last character on line
awk: cmd. line:1: one\nline
awk: cmd. line:1: ^ syntax error
And with single quote, it does not expand the value of the variable:
awk -v var='$variable' 'BEGIN {print var}'
$variable
More info about AWK and variables
Read this faq.
It seems that the good-old ENVIRON awk built-in hash is not mentioned at all. An example of its usage:
$ X=Solaris awk 'BEGIN{print ENVIRON["X"], ENVIRON["TERM"]}'
Solaris rxvt
You could pass in the command-line option -v with a variable name (v) and a value (=) of the environment variable ("${v}"):
% awk -vv="${v}" 'BEGIN { print v }'
123test
Or to make it clearer (with far fewer vs):
% environment_variable=123test
% awk -vawk_variable="${environment_variable}" 'BEGIN { print awk_variable }'
123test
You can utilize ARGV:
v=123test
awk 'BEGIN {print ARGV[1]}' "$v"
Note that if you are going to continue into the body, you will need to adjust
ARGC:
awk 'BEGIN {ARGC--} {print ARGV[2], $0}' file "$v"
I just changed #Jotne's answer for "for loop".
for i in `seq 11 20`; do host myserver-$i | awk -v i="$i" '{print "myserver-"i" " $4}'; done
I had to insert date at the beginning of the lines of a log file and it's done like below:
DATE=$(date +"%Y-%m-%d")
awk '{ print "'"$DATE"'", $0; }' /path_to_log_file/log_file.log
It can be redirect to another file to save
Pro Tip
It could come handy to create a function that handles this so you dont have to type everything every time. Using the selected solution we get...
awk_switch_columns() {
cat < /dev/stdin | awk -v a="$1" -v b="$2" " { t = \$a; \$a = \$b; \$b = t; print; } "
}
And use it as...
echo 'a b c d' | awk_switch_columns 2 4
Output:
a d c b
if I have a string like "sn":"1$$$$12056597.3,2595585.69$$", how can I use awk to split "1$$$$"
I tried
**cat $filename | awk -F "\"1\$\$\$\$" '{ print $2 }'**
**cat $filename | awk -F "\"1$$$$" '{ print $2 }'**
but all failed
any number of $ use
echo '"1$$$$12056597.3,2595585.69$$"' | awk -F '"1[$]+' '{ print $2 }'
exactly 4 use
echo '"1$$$$12056597.3,2595585.69$$"' | awk -F '"1[$]{4}' '{ print $2 }'
to help debug problems with escape characters in the shell you can use the built-in shell command set which will print the arguments that are being passed to awk after the shell has interpreted any escape characters and replaced shell variables
In this case the shell first interprets \$ as an escape for a plain $
set -x
echo '"1$$$$12056597.3,2595585.69$$"'|awk -F "\"1\$\$\$\$" '{ print $2 }'
+ echo '"1$$$$12056597.3,2595585.69$$"'
+ awk -F '"1$$$$' '{ print $2 }'
You can use \$ so the \$ get to awk, but \$ is interpreted in awk regular expressions as a $ anyway. At least awk is nice enough to warn you...
echo '"1$$$$12056597.3,2595585.69$$"'|awk -F "\"1\\$\\$\\$\\$" '{ print $2 }'
+ echo '"1$$$$12056597.3,2595585.69$$"'
+ awk -F '"1\$\$\$\$' '{ print $2 }'
awk: warning: escape sequence `\$' treated as plain `$'
Turn off debugging with
set +x
echo '"1$$$$12056597.3,2595585.69$$"' | awk -F '"1[$]+' '{ print $2 }' |sed 's/.\{3\}$//'
Or if you want to split both float digit:
echo '"1$$$$12056597.3,2595585.69$$"' | awk -F '"1[$]+' '{ print $2 }' |sed 's/.\{3\}$//' |awk 'BEGIN {FS=","};{print $1}'
And
echo '"1$$$$12056597.3,2595585.69$$"' | awk -F '"1[$]+' '{ print $2 }' |sed 's/.\{3\}$//' |awk 'BEGIN {FS=","};{print $2}'
can a user input variable($userinput) compare with a value?
awk -F: '$1 < $userinput { printf .... }'
This comparison expression seems ok to me, but it gives an error?
Try doing this :
awk -vuserinput="$userinput" -F: '$1 < userinput {}'
A real example :
read -p "Give me an integer >>> " int
awk -v input=$int '$1 < input {print $1, "is less than", input}' <<< 1
I need to get 88090000 after zeroes. How can I do that using awk?
There can be any number of zeroes before the number. But, I need the number after the zeroes.
0000000088090000
I appreciate your help.
Just add 0.
$ awk '{ print $0 + 0 }' <<< '0000000088090000'
88090000
Using regular expressions:
echo '0000000088090000' | awk '{ sub(/^0+/, ""); print }'
One way:
echo "0000000088090000" | awk '{ printf "%d\n", $0 }'
Using sed:
[jaypal:~/Temp] echo "0000000088090000" | sed 's/^0\+//g'
88090000
awk 'BEGIN {print FILE}
{printf "Part\t\tStart\t\tEnd"
printf "%s %-6s %-6d",Part1,1,$end1
printf "%s %-6d %-6d",Part2,$start2,$end2}
END {printf "total records:%d", $tot}' >meta.txt
This is my code and is not working. It is a part of a shell script, all the variables are computed in other part of script.
My I/P files are tables, and I have to find out no. of records in them and dispay the results in a file in the form of a table like
File Start End
File1 1 205
file2 206 417
and so on
If those are shell variables, you need to pass them into the AWK script:
awk -v "start2=$start2" -v "end1=$end1" -v "end2=$end2" -v "tot=$tot" 'BEGIN {print FILE}
{printf "Part\t\tStart\t\tEnd"
printf "%s %-6s %-6d", Part1, 1, end1
printf "%s %-6d %-6d", Part2, start2, end2}
END {printf "total records:%d", tot}' >meta.txt
There is only one BEGIN and END block in awk. I actually don't really understanding what you are trying to do. So I expect you to show more examples. however, to create a file table in awk, you can do it in the BEGIN block
awk 'BEGIN{
print "field1\tfield2\n"
...
print "one\ttwo"
...
}' > outputfile.txt
if you have an input file to process, and the table contents comes from this input file
awk 'BEGIN{
print "field1\tfield2\n"
}
{
...
print "one\ttwo"
...
}END{
print "so some final stuff here"
}' inputfile > outputfile.txt