I want to check whether Swap space exist on a centos box in my bash script.Thus in cash there are no swap space on the server , then i can create swap.
I tried this approach
if [[ -n $(swapon -s) ]]; then
:
else
mkswap /dev/vda2 &> /dev/null
swapon /dev/vda2
fi
Obviously it won't work since even when there is no swap swapon -s will return a string
Filename Type Size Used Priority
This works nicely for me:
if free | awk '/^Swap:/ {exit !$2}'; then
echo "Have swap"
else
echo "No swap"
fi
I don't see a means to do this just using 'swapon' since it:
- always returns at least one line
- always returns an error code of '0'
You could 'count lines' and if less then 2 then take the 'else' branch, i.e.
if [[ $(swapon -s | wc -l) -gt 1 ]] ; then echo "OK" ; else echo "Bad" ; fi
OK
if [[ $(swapon -s | wc -l) -gt 2 ]] ; then echo "OK" ; else echo "Bad" ; fi
Bad
Or simply check for 'devices' in the swapon output, i.e.:
if [[ $(swapon -s | grep -ci "/dev" ) -gt 0 ]] ; then echo "OK" ; else echo "Bad" ; fi
Related
I have this variable:
>echo $br_name
srxa wan-a1 br-wan3-xa1 0A:AA:DD:C1:F1:A3 ge-0.0.3 srxa wan-a2 br-wan3-xa2 0A:AA:DD:C1:F2:A3 ge-0.0.3
I am trying to create a conditional where it detects whether ge-0.0.3 is repeated more than 1 time in my variable $br_name
For example:
if [[ $br_name has ge-0.0.3 repeated more than one time ]]
then
echo "ge-0.0.3 is shown more than once"
else
:
fi
Bash's =~ is using extended RE.
[Bash-5.2] % check() { local s='(ge-0\.0\.3.*){2,}'; [[ "$1" =~ $s ]] && echo yes || echo no; }
[Bash-5.2] % check 'xxx'
no
[Bash-5.2] % check 'ge-0.0.3'
no
[Bash-5.2] % check 'ge-0.0.3 ge-0.0.3 '
yes
[Bash-5.2] % check 'ge-0.0.3 ge-0.0.3 ge-0.0.3 '
yes
You can use grep -o to print only the matched phrase. Also use -F to make sure that it matches literal characters instead of a regex where . and - are special
if [[ $(echo "$br_name" | grep -Fo ge-0.0.3 | wc -l) -gt 1 ]]; then
echo "ge-0.0.3 is shown more than once"
else
echo "only once"
fi
For more complex patterns of course you can drop -F and write a proper regex for grep
simple word
If your word would be "easy", you can detect the occurrences count with:
echo "123 123 123" | sed "s/123 /123\n/g" | wc -l
In which the word is replace for the same but with \n and then wc count the lines
or you can try one of these:
Count occurrences of a char in a string using Bash
How to count number of words from String using shell
complex
Since your word is "complex" or you will want a pattern, you will need regex:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions
https://linuxconfig.org/advanced-bash-regex-with-examples
script.sh
count=0
for word in $1; do
if [[ "$word" =~ .*ge-0\.0\.3.* ]]
then
count=$(($count+1))
fi
done
if [ "$count" -gt "1" ];
then
echo "ge-0.0.3 is shown more than once"
else
if [ "$count" -eq "0" ];
then
echo "ge-0.0.3 is not shown"
else
echo "ge-0.0.3 is shown once"
fi
fi
execution
bash script.sh "srxa wan-a1 br-wan3-xa1 0A:AA:DD:C1:F1:A3 ge-0.0.3 srxa wan-a2 br-wan3-xa2 0A:AA:DD:C1:F2:A3 ge-0.0.3"
grep
With grep you can get the ocurrence count
ocurrences=( $(grep -oE '(ge-0\.0\.3)' <<<$1) )
ocurrences_count=${#ocurrences[*]}
echo $ocurrences_count
Assuming you want to do a literal string match on whole words, not substrings, then this might be what you want:
$ if (( $(grep -oFw 'ge-0.0.3' <<<"$br_name" | wc -l) > 1 )); then echo 'yes'; else echo 'no'; fi
yes
I am trying to have a script take an argument and run a command against it and retry the command if a result matches a certain string. Otherwise other results will echo the result.
We have a script at work where we run "rm <filename>" but it takes 5 seconds to return whether successful or not and I want to make a script to keep running it until it sees a "destroyed file" string in the result.
This is what I have so far..
#!/bin/bash
function rm () {
if [[ $(rm $1 | grep -m 1 'destroyed file') ]] ; then
echo "Destroyed File"
elif [[ $(rm $1 | grep -m 1 'remove failed') ]] ; then
sleep 5;
rm $1
elif [[ $(rm $1 | grep -m 1 'not found') ]] ; then
echo "file not found"
elif [[ $(rm $1 | grep -m 1 'You must have root access') ]] ; then
echo "You do not have root access"
else
echo "Incorrect parameter or command"
fi
}
I have a simple command to evaluate if there's enough free disk space on the root partition:
if [ $(df | awk '$6 == "/" {print $4}') -lt 30000 ]; then
echo "Insufficient free disk space"
else
echo "Disk space check OK"
fi
This returns "Disk space check OK" (ie, false), but the actual value returned from the df command is greater than 30000. So, I would expect the comparison to return true:
$ echo $(df | awk '$6 == "/" {print $4}')
38052168
What am I missing here?
Thanks!
Mind the the print "$4" with awk prints the available disk space. If so
you may may use sed for this simple job but need to introduce some error checking as well, just in case, df returns an error.
I may try it like this
avail=$(df --output=avail / 2>/dev/null | sed 1d)
if [ -z "$avail" ] # $avail can be empty only df fails as per this case
then
echo "Error with df"
elif [ "$avail" -lt 30000 ] # Your original logic is correct!!
then
echo "Insufficient Disk Space"
else
echo "Disk Check Passed"
fi
df --output=avail /
gives you output like below
Avail
8708124
38052168 is not less than 30000 that is why the else block is running. instead of -lt use -gt or
if [[ ! com1 -lt com2 ]];then
# do stuff
else
# do stuff
fi
I am dealing with sorting words in Bash according to a given argument. I am given either argument -r, -a , -v or -h and according to it there are options to sort the words, as you can see at my "help".
Somehow, if I pass the argument -r it creates an error. I really don't understand what I am doing wrong, as if[["$arg"=="-a"]] works, but I have to use case somehow.
Here is my code:
#!/bin/bash
# Natalie Zubkova , zubkonat
# zubkonat#cvut.fel.cz , LS
#help
help="This script will calculate occurances of words in a given file, and it will sort them according to the given argument in following order> \n
without parametre = increasing order according to a number of occurance\n
-r = decreasing order according to a number of occurance\n
-a = in alphabetical increasing order\n
-a -r = in alphabetical decreasing order\n
There are also special cases of the given parametre, when the script is not sorting but:\n
-h = for obtaining help \n
-v = for obtaining a number of this task "
# this function will divide a given chain into a words, so we can start calculating the occurances, we also convert all the capital letters to the small ones by - tr
a=0;
r=0;
EXT=0;
if [ "$1" == "-h" ]; then
echo $help
exit 0
fi
if [ "$2" == "-h" ]; then
echo $help
exit 0
fi
if [ "$1" == "-v" ]; then
echo "5"
exit 0
fi
if [ "$2" == "-v" ]; then
echo "5"
exit 0
fi
function swap {
while read x y; do
echo "$y" "$x";
done
}
function clearAll {
sed -e 's/[^a-z]/\n/gI' | tr '[A-Z]' '[a-z]' | sort | uniq -c |awk '{i++; if(i!=1) print $2" "$1}' #swap
}
for arg do
case "$arg" in
"-a")
a=1
;;
"-r")
r=1
;;
"-v")
echo "5" #number of task is 5
exit 0
;;
"-h")
echo $help
exit 0
;;
"-?")
echo "invalid parametre, please display a help using argument h"
exit 0
;;
esac
done
#Sort according to parametres -a and -r
function sortWords {
if [[ a -eq 1 ]]; then
if [[ r -eq 0 ]]; then
clearAll | sort -nk1
fi
fi
if [[ a -eq 1 ]]; then
if [[ r -eq 1 ]]; then
clearAll | sort -nk1 -r
fi
fi
if [[ r -eq 1 ]]; then
if [[ a -eq 0 ]]; then
clearAll | sort -nk2 -r
fi
fi
if [[ a -eq 0 ]]; then
if [[ r -eq 0 ]]; then
clearAll | sort -nk2
fi
fi
}
#code is from Stackoverflow.com
function cat-all {
while IFS= read -r file
do
if [[ ! -z "$file" ]]; then
cat "$file"
fi
done
}
#histogram
hist=""
for arg do
if [[ ! -e "$arg" ]]; then
EXT=1;
echo "A FILE DOESNT EXIST" >&2
continue;
elif [[ ! -f "$arg" ]]; then
EXT=1;
echo "A FILE DOESNT EXIST" >&2
continue;
elif [[ ! -r "$arg" ]]; then
EXT=1;
echo "A FILE DOESNT EXIST" >&2
continue;
fi
done
for arg do
hist="$hist""$arg""\n"
done
echo -e "$hist" | cat-all | sortWords
exit $EXT;
Here is what our upload system which does some test to see if our program works says:
Test #6
> b5.sh -r ./easy.txt
ERROR: script output is wrong:
--- expected output
+++ script stdout
## --- line 1 (167 lines) ; +++ no lines ##
-the 89
-steam 46
-a 39
-of 37
-to 35
...
script written 484 lines, while 484 lines are expected
script error output:
A FILE DOESNT EXIST
cat: invalid option -- 'r'
Try `cat --help' for more information.
script exit value: 1
ERROR: Interrupted due to failed test
If anyone could help me I would really appreciate it.
You forgot to move the parameter index position with shift:
"-r")
r=1
shift
;;
shift above moves to the next command line arg: ./easy.txt in your case.
Without it, read -r file will read -r instead of the file name.
A process (in background) should create a file (e.g. result.txt) and populate it with 5 log lines.
I need to check: 1) if the file exists and 2) checks if all the logs (5 lines) are stored
If these conditions are not satisfy within xxx seconds, the process failed and print "FAILED" in terminal, otherwise print "SUCCEED".
I think I need to use a while loop, but I don't know how to implement these conditions
N.B: the lines are appended into the file (asynchronously) and I don't have to check the compliance of logs, just to check if all are stored
This one checks the log and waits 2 seconds before failing:
#!/bin/sh
log_success() {
[[ $(tail -n "$2" "$1" 2> /dev/null | wc -l) -eq "$2" ]]
}
log_success 'file.log' 5 || sleep 2
if log_success 'file.log' 5; then
echo "success"
else
echo "fail"
fi
Well here's my draft for that:
FILE=/path/to/something
for (( ;; )); do
if [[ -e $FILE ]] && WC=$(wc -l < "$FILE") && [[ WC -ge 5 ]]; then
: # Valid.
fi
done
Or
FILE=/path/to/something
for (( ;; )); do
if [[ ! -e $FILE ]]; then
: # File doesn't exist. Do something.
elif WC=$(wc -l < "$FILE") && [[ WC -ge 5 ]]; then
: # Valid.
else
: # File doesn't contain 5 or more lines or is unreadable. Invalid.
fi
done
This one could still have problems with race conditions though.