#!/bin/bash
LIMIT='50'
DIR="( $(df -Ph | column -t | awk '{print $5}' | grep -v Use) )"
for i in $DIR;
do
USED=$(df -Ph $i | awk '{print $5}' | sed -ne 2p | cut -d"%" -f1)
if [ "$USED" -gt "$LIMIT" ];
#If used space is bigger than LIMIT
then
#####
fi
done
Why am I getting syntax error at line 5 ? in for loop for variable $DIR?
I think the fundamental error is the quotes in the assignment of the array. Instead of DIR="( $(...) )", you need to drop the quotes and use DIR=( $(...) ). However, that assignment isn't necessary at all!
You probably shouldn't parse df like this, but you definitely should not be running df multiple time. There's no need for the embedded loop. Since you haven't really should what you're doing in the cases when the filesystem use is over the limit, it's hard to give better code, but whatever you're doing there can almost certainly be done easily in awk. Or, if not in awk, you can use awk rather than the embedded loop to trigger the action. eg, you could just do:
df -Ph | awk 'NR>1{printf("%s: %s than limit\n", $1, $5 + 0> limit ? "bigger" : "smaller")}' limit="${LIMIT-50}"
altough it probably makes more sense to do:
df -Ph | awk 'NR>1 && $5 + 0 > limit {print $1 " is over limit" > "/dev/stderr"}' limit="${LIMIT-50}"
note that both of these fail horribly if any of the column of the output of df contain whitespace (eg "map auto_home"). The output of df is intended for human consumption, and is not really suited to this sort of thing. You could do a column count in the awk (or use $(NF-1) instead of $5) and get the Capacity that way, but that's just moving the fragility.
Related
Here is the part of my script that uses awk.
ids=`cut -d ',' -f1 $file | sed ':a;N;$!ba;s/\n/,/g'`
awk -vdata="$ids" -F',' 'NR > 1 {if(index(data,$2)>0){print $0",true"}else{print $0",false"}}' $input_file >> $output_file
This works perfectly, but when I tried to get data to two or more files like this.
ids=`cut -d ',' -f1 $file1 $file2 $file3 | sed ':a;N;$!ba;s/\n/,/g'`
It returned this error.
/usr/bin/awk: Argument list too long
As I researched, it was not caused by the number of files, but the number of ids fetched.
Does anybody have an idea on how to solve this? Thanks.
You could use an environment variable to pass the data to awk. In awk the environment variables are accessible via an array ENVIRON.
So try something like this:
export ids=`cut -d ',' -f1 $file | sed ':a;N;$!ba;s/\n/,/g'`
awk -F',' 'NR > 1 {if(index(ENVIRON["ids"],$2)>0){print $0",true"}else{print $0",false"}}' $input_file >> $output_file
Change the way you generate your ids so they come out one per line, like this, which I use as a very simple way to generate ids 2,3 and 9:
echo 2; echo 3; echo 9
2
3
9
Now pass that as the first file to awk and your $input_file as the second file to awk:
awk '...' <(echo 2; echo 3; echo 9) "$input_file"
In bash you can generate a pseudo-file with the output of a process using <(some commands), and that is what I am using.
Now, in your awk, pick up the ids from the first file like this:
awk 'FNR==NR{ids[$1]++;next}' <(echo 2; echo 3; echo 9)
which will set ids[2]=1, ids[3]=1 and ids[9]=1.
Then pass both your files and add in your original processing:
awk 'FNR==NR{ids[$1]++;next} {if($2 in ids) print $0",true"; else print $0",false"}' <(echo 2; echo 3; echo 9) "$input_file"
So, for my final answer, your entire code will look like:
awk 'FNR==NR{ids[$1]++;next} {if($2 in ids) print $0",true"; else print $0",false"}' <(cut ... file1 file2 file3 | sed ...) "$input_file"
As #hek2mgl alludes in the comments, you can likely just pass the files which include the ids to awk "as is" and let awk find the ids itself rather than using cut and sed. If there are many, you can make them all come to awk as the first file with:
awk '...' <(cat file1 file2 file3) "$input_file"
There's 2 problems in your script:
awk -vdata="$ids" -F',' 'NR > 1 {if(index(data,$2)>0){print $0",true"}else{print $0",false"}}' $input_file >> $output_file
that could be causing that error:
-vdata=.. - that is gawk-specific, in other awks you need to leave a space between -v and data=. So if you aren't running gawk then idk what your awk will make of that statement but it might treat it as multiple args.
$input_file - you MUST quote shell variables unless you have a specific purpose in mind by leaving them unquoted. If $input_file contains globbing chars or spaces then you leaving it unquoted will cause them to be expanded into potentially multiple files/args.
So try this:
awk -v data="$ids" -F',' 'NR > 1 {if(index(data,$2)>0){print $0",true"}else{print $0",false"}}' "$input_file" >> "$output_file"
and see if you still have the problem. Your script does have other unrelated issues of course, some of which have already been pointed out, and you can post a followup question if you want help with those, but just FYI that awk script could be written more concisely as:
awk -v data="$ids" 'BEGIN{FS=OFS=","} NR > 1{print $0, (index(data,$2) ? "true" : "false")}'
I'm learning bash, and here's a short script to assign deciles to the second column of file $1.
The complicating bit is the use of awk within the script, leading to ambiguous redirects when I run the script.
I would have gotten this done in SAS by now, but like the idea of two lines of code doing the job.
How can I communicate the total number of rows (${N}) to awk within the script? Thanks.
N=$(wc -l < $1)
cat $1 | sort -t' ' -k2gr,2 | awk '{$3=int((((NR-1)*10.0)/"${N}")+1);print $0}'
You can set an awk variable from the command line using -v.
N=$(wc -l < "$1" | tr -d ' ')
sort -t' ' -k2gr,2 "$1" | awk -v n=$N '{$3=int((((NR-1)*10.0)/n)+1);print $0}'
I added tr -d to get rid of the leading spaces that wc -l puts in its result.
I want to compare two string variables and print the characters that are the same for both. I'm not really sure how to do this, I was thinking of using comm or diff but I'm not really sure the right parameters to print only matching characters. also they say they take in files and these are strings. Can anyone help?
Input:
a=$(echo "abghrsy")
b=$(echo "cgmnorstuvz")
Output:
"grs"
You don't need to do that much work to assign $a and $b shell variables, you can just...
a=abghrsy
b=cdgmrstuvz
Now, there is a classic computer science problem called the longest common subsequence1 that is similar to yours.
However, if you just want the common characters, one way would let Ruby do the work...
$ ruby -e "puts ('$a'.chars.to_a & '$b'.chars.to_a).join"
1. Not to be confused with the different longest common substring problem.
Use Character Classes with GNU Grep
The isn't a widely-applicable solution, but it fits your particular use case quite well. The idea is to use the first variable as a character class to match against the second string. For example:
a='abghrsy'
b='cgmnorstuvz'
echo "$b" | grep --only-matching "[$a]" | xargs | tr --delete ' '
This produces grs as you expect. Note that the use of xargs and tr is simply to remove the newlines and spaces from the output; you can certainly handle this some other way if you prefer.
Set Intersection
What you're really looking for is a set intersection, though. While you can "wing it" in the shell, you'd be better off using a language like Ruby, Python, or Perl to do this.
A Ruby One-Liner
If you need to integrate with an existing shell script, a simple Ruby one-liner that uses Bash variables could be called like this inside your current script:
a='abghrsy'
b='cgmnorstuvz'
ruby -e "puts ('$a'.split(//) & '$b'.split(//)).join"
A Ruby Script
You could certainly make things more elegant by doing the whole thing in Ruby instead.
string1_chars = 'abghrsy'.split //
string2_chars = 'cgmnorstuvz'.split //
intersection = string1_chars & string2_chars
puts intersection.join
This certainly seems more readable and robust to me, but your mileage may vary. At least now you have some options to choose from.
Nice question +1.
You can use an awk trick to get this done.
a=abghrsy
b=cdgmrstuvz
comm -12 <(echo $a|awk -F"\0" '{for (i=1; i<=NF; i++) print $i}') <(echo $b|awk -F"\0" '{for (i=1; i<=NF; i++) print $i}')|tr -d '\n'
OUTPUT:
grs
Note use of awk -F"\0" that breaks input string character by character into different awk fiedls. Rest is pretty straightforward use of comm and tr.
PS: If you input string is not sorted then you need to pipe awk's output to sort or do sort of an array inside awk.
UPDATE: awk only solution (without comm):
echo "$a;$b" | awk -F"\0" '{scnd=0; for (i=1; i<=NF; i++) {if ($i!=";") {if (!scnd) arr1[$i]=$i; else if ($i in arr1) arr2[$i]=$i} else scnd=1}} END { for (a in arr2) printf("%s", a)}'
This assumes semicolon doesn't appear in your string (you can use any other character if that's not the case).
UPDATE 2: I think simplest solution is using grep -o
(thanks to answer from #CodeGnome)
echo "$b" | grep -o "[$a]" | tr -d '\n'
Using gnu coreutils(inspired by #DigitalRoss)..
a="abghrsy"
b="cgmnorstuvz"
echo "$(comm -12 <(echo "$a" | fold -w1 | sort | uniq) <(echo "$b" | fold -w1 | sort | uniq) | tr -d '\n')"
will print grs. I assumed you only want uniq characters.
UPDATE:
Modified for dash..
#!/bin/dash
string1=$(printf "$1" | fold -w1 | sort | uniq | tr -d '\n');
string2=$(printf "$2" | fold -w1 | sort | uniq | tr -d '\n');
while [ "$string1" != "" ]; do
c1=$(printf '%s\n' "$string1" | cut -c 1-1 )
string2=$(printf "$2" | fold -w1 | sort | uniq | tr -d '\n');
while [ "$string2" != "" ]; do
c2=$(printf '%s\n' "$string2" | cut -c 1-1 )
if [ "$c1" = "$c2" ]; then
echo "$c1\c"
fi
string2=$(printf '%s\n' "$string2" | cut -c 2- )
done
string1=$(printf '%s\n' "$string1" | cut -c 2- )
done
echo;
Note: I am just a beginner. There might be a better way of doing this.
I have a small bash file which I intend to use to determine my current ping vs my average ping.
#!/bin/bash
output=($(ping -qc 1 google.com | tail -n 1))
echo "`cut -d/ -f1 <<< "${output[3]}"`-20" | bc
This outputs my ping - 20 ms, which is the number I want. However, I also want to prepend a + if the number is positive and append "ms".
This brings me to my overarching problem: Bash syntax regarding escaping and such heavy "indenting" is kind of flaky.
While I'll be satisfied with an answer of how to do what I wanted, I'd like a link to, or explanation of how exactly bash syntax works dealing with this sort of thing.
output=($(ping -qc 1 google.com | tail -n 1))
echo "${output[3]}" | awk -F/ '{printf "%+fms\n", $1-20}'
The + modifier in printf tells it to print the sign, whether it's positive or negative.
And since we're using awk, there's no need to use cut or bc to get a field or do arithmetic.
Escaping is pretty awful in bash if you use the deprecated `..` style command expansion. In this case, you have to escape any backticks, which means you also have to escape any other escapes. $(..) nests a lot better, since it doesn't add another layer of escaping.
In any case, I'd just do it directly:
ping -qc 1 google.com.org | awk -F'[=/ ]+' '{n=$6}
END { v=(n-20); if(v>0) printf("+"); print v}'
Here's my take on it, recognizing that the result from bc can be treated as a string:
output=($(ping -qc 1 google.com | tail -n 1))
output=$(echo "`cut -d/ -f1 <<< "${output[3]}"`-20" | bc)' ms'
[[ "$output" != -* ]] && output="+$output"
echo "$output"
Bash cannot handle floating point numbers. A workaround is to use awk like this:
#!/bin/bash
output=($(ping -qc 1 google.com | tail -n 1))
echo "`cut -d/ -f1 <<< "${output[3]}"`-20" | bc | awk '{if ($1 >= 0) printf "+%fms\n", $1; else printf "%fms\n", $1}'
Note that this does not print anything if the result of bc is not positive
Output:
$ ./testping.sh
+18.209000ms
Expecting this to print out abc - but I get nothing, every time, nothing.
echo abc=xyz | g="$(awk -F "=" '{print $1}')" | echo $g
A pipeline isn't a set of separate assignments. However, you could rewrite your current code as follows:
result=$(
echo 'abc=xyz' | awk -F '=' '{print $1}'
)
echo "$result"
However, a more Bash-centric solution without intermediate assignments could take advantage of a here-string. For example:
awk -F '=' '{print $1}' <<< 'abc=xyz'
Other solutions are possible, too, but this should be enough to get you started in the right direction.