(NOTE: this is a bash question, not k8s)
I have a working script which will fetch the name
admin-job-0
from a list of kubernetes cronjobs, of which there can be up to 32 ie. admin-job-0 -1, -2, -3 ... -31
Question: How do I grep "-$1$" ie a dash, the number, and no more, instead of just the number as I have below?
Bonus question: Is there any way to do what I'm doing below without the if/else logic regardless of whether there's an argument passed?
fetch-admin-job() {
if [[ -n $1 ]]; then
name=$(kubectl get cronjob | awk '/^admin-job.*/{print $1}' | grep $1 )
else
# get the first one (if any)
name=$(kubectl get cronjob | awk '/^admin-job.*/{print $1}')
fi
echo $name
}
#example:
fetch-admin-job 0
You can replace your function code with this:
fetch-admin-job() {
kubectl get cronjob |
awk -v n="$1" '!n || $1 == "admin-job-" n {print $1}'
}
Then invoke it as:
fetch-admin-job 0
fetch-admin-job 4
fetch-admin-job
We are using this condition in awk:
!n: will be true when you don't pass anything in first argument
||: OR
$1 == "admin-job-" n: Will be used to compare first column in output of kubectl command with first argument you pass. Note that this is equivalent of awk '/^admin-job/ ...' | grep "-$1$".
You don't need to use grep on an awk output as awk can handle that part as well.
If you pass to grep a double-hyphen (--), this signals the end of the option and a dash at the start of the pattern does not harm, i.e.
grep -- "$1"
or
grep -- "$1$"
or whatever you want to achieve.
Related
Need 2 arguments in awk command for one column.
Script, name todo.
#!/bin/bash
folder_main="$( cd $( dirname "${BASH_SOURCE[0]}" ) >/dev/null 2>&1 && pwd )"
if [ $1 = 'e' ]; then
mcedit $folder_main/kb/todo.kb
else
awk -F ',' '$1=="'$1'"' $folder_main/kb/todo.kb
fi
Expectation is when I write todo i, it will grep me lines with i OR c by the first column divided by ,.
I tried this.
awk -F ',' '$1=="{c|'$1'}"' $folder_main/kb/todo.kb
But nothing.
Thanks.
You should pass your shell variable to awk using -v and fix your awk syntax:
awk -F, -v a="$1" '$1 == "c" || $1 == a' "$folder_main/kb/todo.kb"
This sets the awk variable a to the value of the shell positional parameter $1, and prints the line if the first column is either "c" or whatever you passed as the first argument to the script.
You could also shorten the line slightly by using a regular expression match instead of two ==:
awk -F, -v a="$1" '$1 ~ "^(c|"a")$"' "$folder_main/kb/todo.kb"
Although I think that the first option is easier to read, personally. It is also safer to use, as a character with special meaning inside a regular expression (such as *, [, ( or {) could cause the script to either fail or behave in an unexpected way.
You can't use shell variables directly in awk like this. Instead you pass them into your awk script using the -v flag:
awk -F ',' -v searchterm=$1 '$1==searchterm' $folder_main/kb/todo.kb
The problem is the following I have a file that each line has this form:
id|lastName|firstName|gender|birthday|joinDate|IP|browser
i want to sort alphabetically all the firstnames in that file and print them one on each line but each name only once
i have created the following program but for some reason it creates an infinite loop:
array1=()
while read LINE
do
if [ ${LINE:0:1} != '#' ]
then
IFS="|"
array=($LINE)
if [[ "${array1[#]}" != "${array[2]}" ]]
then
array1+=("${array[2]}")
fi
fi
done < $3
echo ${array1[#]} | awk 'BEGIN{RS=" ";} {print $1}' | sort
NOTES
if [ ${LINE:0:1} != '#' ] : this command is used because there are comments in the file that i dont want to print
$3 : filename
array1 : is used for all the seperate names
Wow, there's a MUCH simpler and cleaner way to achieve this, without having to mess with the IFS variable or using arrays. You can use "for" to do this:
First I created a file with the same structure as yours:
$ cat file
id|lastName|Douglas|gender|birthday|joinDate|IP|browser
id|lastName|Tim|gender|birthday|joinDate|IP|browser
id|lastName|Andrew|gender|birthday|joinDate|IP|browser
id|lastName|Sasha|gender|birthday|joinDate|IP|browser
#id|lastName|Carly|gender|birthday|joinDate|IP|browser
id|lastName|Madson|gender|birthday|joinDate|IP|browser
Here's the script I wrote using "for":
#!/bin/bash
for LINE in `cat file | grep -v "^#" | awk -F'|' '{print$3}' | sort -u`
do
echo $LINE
done
And here's the output of this script:
$ ./script.sh
Andrew
Douglas
Madson
Sasha
Tim
Explanation:
for LINE in `cat file`
Creates a loop that reads each line of "file". The commands between ` are run by linux, for example, if you wanted to store the date inside of a variable you could use "VARDATE=`date`".
grep -v "^#"
The option -v is used to exclude results matching the pattern, in this case the pattern is "^#". The "^" character means "line begins with". So grep -v "^#" means "exclude lines beginning with #".
awk -F'|' '{print$3}'
The -F option switches the column delimiter from the default (the default is a space) to whatever you put between ' after it, in this case the "|" character.
The '{print$3}' prints the 3rd column.
sort -u
And the "sort -u" command to sort the names alphabetically.
I made a small script to kill PID's if they exceed expected cpu usage. It works, but there is a small problem.
Script:
while [ 1 ];
do
cpuUse=$(ps -eo %cpu | sort -nr | head -1)
cpuMax=80
PID=$(ps -eo %cpu,pid | sort -nr | head -1 | cut -c 6-20)
if [ $cpuUse -gt $cpuMax ] ; then
kill -9 "$PID"
echo Killed PID $PID at the usage of $cpuUse out of $cpuMax
fi
exit 0
sleep 1;
done
It works if the integer is three digits long but fails if it drops to two and displays this:
./kill.sh: line 7: [: 51.3: integer expression expected
My question here is, how do I make bash understand the divider so it can kill processes under three digits.
You are probably getting leading space in that variable. Try piping with tr to strip all spaces first:
cpuUse=$(ps -eo %cpu | sort -nr | head -1 | tr -d '[[:space:]]')
Remove text after dot from cpuUse variable:
cpuUse="${cpuUse%%.*}"
Also better to use quotes in if condition:
if [ "$cpuUse" -gt "$cpuMax" ] ; then
OR better use arithmetic operator (( and )):
if (( cpuUse > cpuMax )); then
As you see, bash doesn't grok non-integer numbers. You need to eliminate the decimal point and the following digits from $cpuUse before doing the comparison":
cpuUse=$(sed 's/\..*/' <<<$cpuUse)
However, this is really a job for awk. It will simplify much of what you're doing. Whenever you find yourself with greps of greps, or head and then cuts, you should be dealing with awk. Awk can easily combine these multiple piped seds, greps, cuts, heads, into a single command.
By the way, the correct ps command is:
$ ps -eocpu="",pid=""
Using the ="" will eliminate the heading and simply give you the CPU and PID.
Looking at your program, there's no real need to sort. You're simply looking for all processes above that $cpuMax threshold:
ps -eo %cpu="",pid="" | awk '$1 > 80 {print $2}'
That prints out your PIDs which are over your threshold. Awk automatically loop through your entire input line-by-line. Awk also automatically divides each line into columns, and assigns each a variable from $1 and up. You can change the field divider with the -F parameter.
The above awk says look for all lines where the first column is above 80%, (the CPU usage) and print out the second column (the pid).
If you want some flexibility and be able to pass in different $cpuMax, you can use the -v parameter to set Awk variables:
ps -eo %cpu="",pid="" | awk -vcpuMax=$cpuMax '$1 > cpuMax {print $2}'
Now that you can pipe the output of this command into a while to delete all those processes:
pid=$(ps -eo %cpu="",pid="" | awk -vcpuMax=$cpuMax '$1 > cpuMax {print $2}')
if [[ -n $pid ]]
then
kill -9 $pid
echo "Killed the following processes:" $pid
fi
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'm trying to create a shell script and the fact is, I want to change the output if the variable $output is filled. I was thinking about checking the variable with an if inside the command but I don't know if it's the correct syntax. Here is an exemple (of course that doesn't work):
ls -lisa | awk '$5 == own' own="$owner" | sort -k$column -n if [
$output ]; then print > out.txt fi
I don't know if it's going to work that way and if it's possible.
The exec built-in can change the default standard output for the rest of the running shell script. So, in this case, you would do:
if [ -n "$output" ]; then
exec >out.txt
fi
ls -lisa | awk '$5 == own' own="$owner" | sort -k$column
I'm not entirely sure what you're trying to do with the awk part, so this is just verbatim from your question.
Another option is to put the part of your script that you want to redirect into a function, and then call the function in one of two ways, redirecting the output. Example:
do_work() {
ls -lisa | awk '$5 == own' own="$owner" | sort -k$column
}
if [ -n "$output" ]; then
do_work >out.txt
else
do_work
fi
You can use the shell's "use default value" option (${variable:-default}, with /dev/stdout as the default) to do this:
ls -lisa | awk '$5 == own' own="$owner" | sort -k$column -n > "${output:-/dev/stdout}"