i have a variable that when i echo it looks like this:
#echo $var
awk '{print $7 " " $6 " " $8 " "}'
but if I try something like
#ls -lah | exec $var
awk: '{print
awk: ^ invalid char ''' in expression
What am I doing wrong?
Instead of exec you need to call eval:
ls -lah | eval $var
However 2 cautions here:
Parsing ls output should be avoided
Use of eval should be minimised
Just put the awk script in a variable
var='{print $7 " " $6 " " $8 " "}'
ls -lah | awk "$var"
Related
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}'
because i haven't found a solution on google or the searchfunction i will ask here.
Here is my code :
Send="last -n 1 $1 | awk '{ print $1 " " $2 }'"
My problem is, that my shell script is using parameters.
When i'm calling my script:
myScript hello world
Then my awk-Command looks like
awk '{ print hello " " world }'
But how could I avoid this? is there a way?
Because this is a part of a project, i couldn't post more code. ;/
first change the outer "'s to $() so: send=$(last -n 1 $1 | awk '{print $1 " " $2}')
use the FS (field separator) variable which defaults to space in awk instead of " " for a space so: send=$(last -n 1 $1 | awk '{print $1 FS $2}')
Here is a simplified version of my problem.
if (echo "AA BB CC" | awk '{ print $1 $2 }' | grep -q "B"); then
echo $2
fi
I would like to make $2 available in bash, so I can use it elsewhere in the script.
Can that be done?
Update
I realized that I had simplified the problem too much. The awk expression should have been awk '{ print $1 $2 }' instead of just awk '{ print $2 }' which I originally posted.
You can use set:
set -- `echo "AA BB CC" | awk '{print $2}'`
case $1 in *B*) echo $1;; esac
... or if you used the awk just to split the output, let set do that part as well:
set -- `echo "AA BB CC"`
case $2 in *B*) echo $2;; esac
Remember the output of awk, test it for the regular expression and print it:
output=$( echo "AA BB CC" | awk '{ print $2 }' )
if grep -q B <<< "$output" ; then echo "$output" ; fi
You can capture stdout into a variable by using the backtick operator, e.g.
a=`echo foo`
echo $a
For your example, it would be something like:
a=`echo "AA BB CC" | awk '{ print $2 }' | grep -q "B"`
echo $a
I would like to turn the outut of a shell command into a variable e.g. $result and then print it out on screen e.g. print $result
df -H | grep -vE '^Filesystem|tmpfs|cdrom' | awk '{ print $5 " " $1 }'
Just use backticks, and careful with the quoting:
my $result = `df -H | grep -vE '^Filesystem|tmpfs|cdrom' | awk '{ print \$5 " " \$1 }'`;
print $result;
I'm just a learner myself but I found this http://perldoc.perl.org/Shell.html useful... "This package is included as a show case, illustrating a few Perl features. It shouldn't be used for production programs".
I need to execute a command per line of some file. For example:
file1.txt 100 4
file2.txt 19 8
So my awk script need to execute something like
command $1 $2 $3
and save the output of command $1 $2 $3, so system() will not work and neither will getline. (I can't pipe the output if I do something like this.)
The restriction to this problem is to use only awk. (i already had a solution with bashscriot + awk...but I only want awk...just to know more about this)
What's wrong with using getline?
$ ./test.awk test.txt
# ls -F | grep test
test.awk*
test.txt
# cat test.txt | nl
1 ls -F | grep test
2 cat test.txt | nl
3 cat test.awk
# cat test.awk
#!/usr/bin/awk -f
{
cmd[NR] = $0
while ($0 | getline line) output[NR] = output[NR] line RS
}
END {
for (i in cmd) print "# " cmd[i] ORS output[i]
}
Awk's system() function passes the string to /bin/sh, so you can use redirect operators, like ">file.out" if you want.
awk '{system("command " $1 " " $2 " " $3 ">" $1 ".out");}'
Edit: ok, by save, you mean into an awk variable. ephemient is on the right track, then. That's what awk's getline does, like backticks or $(cmd) in shell/perl. In fact, google for awk backticks found this:
http://www.omnigroup.com/mailman/archive/macosx-admin/2006-May/054665.html
You say you can't use getline because then you couldn't pipe. But you can work around that with tee and file-descriptor tricks. This works if /bin/sh is bash:
{ "set +o posix; command " $1 " " $2 " " $3 " | tee >(grep foo)" | getline var; print toupper(var); } # bash-only, and broken.
set +o posix is necessary because awk runs bash as sh, which makes it go into posix mode after readings its startup files. Hmm, I'm not having any luck getting that to work, and it requires bash anyway.
Ok, this works:
$ touch foo bar
$ echo "foo bar" |
awk '{ "{ ls " $1 " " $2 " " $3 " | tee /dev/fd/10 | grep foo > /dev/tty; } 10>&1" | getline var; print toupper(var); }'
foo
BAR