I have a script sh startAWS.sh.
On top of it, i checked this :
if [[ `ps -acx|grep postgres|wc -l` < 1 ]]; then
echo "You need to start your Postgres service to run this script."
ps -acx|grep postgres|wc -l
exit 0
fi
When I run , I got
⚡️ laravel sh startAWS.sh
You need to start your Postgres service to run this script.
6
Hmm... what... 🤦🏻♂️
My Postgres is running, that echo should not be executed.
It shows 6, and 6 is not less than 1, that code should not be executed.
Does anyone know why I echo is printing out?
You need to perform a numeric comparison so use -lt or -gt in your check.
Comparing numbers in Bash
if [[ `ps -acx|grep postgres|wc -l` -lt 1 ]];
There are a couple of problems here.
First, as #RameshNaidu pointed out, inside [[ < ]] is doing string comparison (i.e. alphabetical order) rather than numeric, and that's causing trouble. The usual problem this mistake causes is that string sorting order is different than numeric order -- for instance, [[ 10 < 2 ]] evaluates to true, because "1" comes before "2" in character sorting order. But that doesn't apply here, because "6" comes after "1" in sorting order as well. What's happening is subtler than that: wc -l prints a number of spaces before the number of lines, and space does come before "1", so [[ " 6" < 1 ]] evaluates to true.
Second, ps | grep something is a bad way to check whether a process is running, because (depending on the exact timing) the ps command may include "grep something" in its output, and the grep command will match that. If you have pgrep available, use that instead, since it automatically avoids this problem. Another common workaround is to use grep "[s]omething" instead -- the brackets prevent it from matching itself, so you don't get this extra match.
But there's also a much simpler way to see if there were any matches: rather than using wc to count matches, just use grep -q (or pgrep -q) to suppress output, and just check its exit status (success = found at least one match, so negate it with ! to check for no match). It'll look like one of these:
if ! pgrep -q postgres; then
echo "You need to start your Postgres service to run this script."
or
if ! ps -acx |grep -q "[p]ostgres"; then
echo "You need to start your Postgres service to run this script."
Related
I have script with name : run.sh
This is my script code :
#!/usr/bin/env bash
install() {
sudo apt-get update
sudo apt-get upgrade
}
if [ "$1" = "install" ]; then
install
else
if [ ! -f ./tg/tgcli ]; then
echo "tg not found"
echo "Run $0 install"
exit 1
fi
#sudo service redis-server restart
#./tg/tgcli -s ./bot/bot.lua -l 1 -E $#
./tg/tgcli -s ./bot/bot.lua $#
fi
and when run this script give me output like this every second :
[09:54] 2014 Hello
[09:55] 2014 Hi
[09:57] 2014 How Are you ?
and many like this (thousands in hour !)
and my server get slow in 5 hour.
i check print commands in bot.lua but there are no way to remove print it.
can you add some codes to clear my script logs every 10 second ?
Thanks a lot.
My Script Output Doesn't Save Anywhere and Just Show me in terminal
I want a code such as clear command on linux terminal , clear my script logs every 10 minute or 5 minute.
After 5 day of script running i can (sometimes can't) login my server and my server get very slow and i must wait 3 or 5 minute to login my server and this amazing after login my server my server again get fast !
and i forgot say i use byobu screen for run my scripts and I think screen get my server slow down.
I don't think that something as simple as this would cause your server to slow down, but you can add a check to your script to calculate the size or line count of your log file every time it runs.
This function assumes you are redirecting your output to a log file. Set the variables to whatever makes the most sense.
log_check() {
line_count=$(wc -l $log_file | awk '{print $1}')
size_check=$(du -ax $log_file | awk '{print $1}')
max_file_size="1500"
max_file_length="1000"
if [[ $line_count >= $max_file_length || $size_check >= $max_file_size ]]; then
echo "" > $log_file
fi
}
I would also recommend using [[ ]] over [ ] since this is a bash script, as long as you don't plan in it being posix compliant and only plan on using it with bash [[]] is always better than [].
EDIT:
Since you are logging output to the terminal and not a file you can literally use the clear command in your script.
Try this out and see how the functionality works
for i in {1..20}; do
echo $i
if (( i == 10 )); then
clear
fi
done
I'm assuming your code has a loop somewhere, if not it will be a bit more complex to clear the terminal session. I'm not really sure what part of your code is actually printing anything to stdout, I'm guessing it's this piece here
./tg/tgcli -s ./bot/bot.lua $#
You could try something like this, which will background your initial process and then run clear every 60 seconds to clear the terminal window. Is there any reason you're not writing the output to a log file? That alone could solve some of your issues as well.
#!/bin/bash
./tg/tgcli -s ./bot/bot.lua $# &
pid="$!"
check_pid() {
ps -ef |grep "$pid"|grep -v 'grep' &>/dev/null
}
cnt=1
until ! check_pid; do
if (( cnt == 6 )); then
clear
cnt=1
fi
sleep 10
((cnt++))
done
I have a small script that I am working on. This is only the second script that I have made using bash script.
Basically what I am wanting this script to do is take the users input and fire a command based on that choice.
As you can see the user first enters the host address of the instance they are going to ssh into and ultimately tail logs on. There are a couple things that I am not understanding.
If / Then / Else / Elif - The concept seems simple enough but perhaps how these should be used eludes me.
When I run my script through a bash parser, the parser comes back with the following message:
Line 2:
if [ "$mainmenuinput" = "1" ]; then
^-- SC2154: mainmenuinput is referenced but not assigned.
mainmenu() {
if [ "$mainmenuinput" = "1" ]; then
ssh "$customerurl" tail -f /data/jirastudio/jira/j2ee_*/log/main/current
elif [ "$mainmenuinput" = "2" ]; then
ssh "$customerurl" tail -f /data/jirastudio/confluence/j2ee_*/log/main/current
elif [ "$mainmenuinput" = "3" ]; then
ssh "$customerurl" tail -f /data/jirastudio/horde/service/log/main/current
elif [ "$mainmenuinput" = "4" ]; then
ssh "$customerurl" tail -f /data/jirastudio/apache/logs/access_log
fi
}
printf "\nEnter the customers host URL:\n"
read -r customerurl
printf "Press 1 for JIRA\n"
printf "Press 2 for Confluence\n"
printf "Press 3 for Horde\n"
printf "Press 4 for Apache Access\n"
printf "Press 5 for Apache Error\n"
read -p -r "Make your choice:" "$mainmenuinput"
Looking up the SC2154 entry I found that it means this:
ShellCheck has noticed that you reference a variable that is not assigned. Double check that the variable is indeed assigned, and that the name is not misspelled.
I am a little confused on what that means. If someone can explain that, I would greatly appreciate it.
As it stands, when I run the script, it pauses to wait for the user to enter the host address. The user hits ENTER and the script then presents them with the menu to have them choose which log they want to tail. The menu looks a little odd:
Press 1 for JIRA
Press 2 for Confluence
Press 3 for Horde
Press 4 for Apache Access
Press 5 for Apache Error
-r
Im not sure why the -r is showing up at the end of the menu. When a selection is made, the script ends and outputs this:
./tail_logs.sh: line 23: read:Make your choice:': not a valid identifier`
Any help with this would be appreciated or if anything a push in the right direction. I love figuring this stuff out but sometimes, its helpful to get shoved at least in the general direction of the error/resolution.
Thanks
EDIT 1
Ok, I updated my script with your suggestions. It seemed to still balk at a few things. For example:
(mainmenu "$customerurl" "$mainmenuinput")
Using ShellCheck I got back this:
Line 1:
(mainmenu "$customerurl" "$mainmenuinput") {
^-- SC2154: customerurl is referenced but not assigned.
^-- SC2154: mainmenuinput is referenced but not assigned.
^-- SC1070: Parsing stopped here. Mismatched keywords or invalid parentheses?
If I write this out like:
mainmenu() { then it does not complain. Also, if I run the script with it typed out as per the suggested way, I get an error about `syntax error near unexpected token '{'
The current code looks like this:
#!/bin/sh
mainmenu() {
echo "$1"
echo "$2"
if [ "$2" = "1" ]; then
ssh "$1" tail -f "/data/jirastudio/jira/j2ee_*/log/main/current"
elif [ "$2" = "2" ]; then
ssh "$1" tail -f "/data/jirastudio/confluence/j2ee_*/log/main/current"
elif [ "$2" = "3" ]; then
ssh "$1" tail -f "/data/jirastudio/horde/service/log/main/current"
elif [ "$2" = "4" ]; then
ssh "$1" tail -f "/data/jirastudio/apache/logs/access_log"
elif [ "$2" > 4 || < 1 ]; then
echo "Uh uh uh, you didnt say the magic word! The number you picked isnt in the list. Pick again."
fi
}
echo
echo "Enter the customers host address:"
read -r customerurl
echo "Press 1 for JIRA"
echo "Press 2 for Confluence"
echo "Press 3 for Horde"
echo "Press 4 for Apache Access"
echo "Press 5 for Apache Error"
read -r -p "Pick a number: " mainmenuinput
I get no errors when running this. But when I make a selection, the script ends and does not output the tail command at all. Also, Im not sure if I am validating user input outside of 1-4 correctly with the last elif statement although if I change this to else I get an error when I run the script.
I think my issue is in the first part of the function?
mainmenu() {
echo "$1"
echo "$2"
Without having $hostAddress and mainMenuInput does the script not know what should be assigned to $1 and $2 or does it automatically assign the first thing typed in to these variables?
The main problems are with the read command at the end. First, whatever immediately follows the -p option is used as a prompt string; in this case, the next argument is "-r", so it prints that as a prompt. You clearly want "Make your choice:" to be the prompt, so that must go immediately after -p (i.e. use either read -r -p "Make your choice:" ... or read -p "Make your choice:" -r ...). Second, when you use $mainmenuinput, it replaces that with the current value of mainmenuinput. In the shell, you use $variable to get the value of a variable, not to set it. With both of these problems corrected, the last command becomes:
read -p "Make your choice:" -r mainmenuinput
There's also another important thing: after reading the users' input, you need to actually call the mainmenu function. So just add mainmenu as the last line.
As for the if ... then ... elif ... structure, yours looks fine; I'm not sure what the question is. Although personally I'd add an else clause that printed an error that the option was not valid.
I do have some stylistic/best practice recommendations, though:
It's best to pass information to functions in the form of arguments, rather than global variables. That is, rather than using customerurl and mainmenuinput directly in the function, pass them as arguments (mainmenu "$customerurl" "$mainmenuinput"), then reference those arguments ("$1" and "$2") inside the functions. This doesn't matter much in a small script like this, but having clear distinctions between the variables used by different parts of a program makes things much easier to keep straight in larger programs.
In shell scripts, printf is the best way to do complex things like printing lines without a linefeed at the end, or translating escape characters... but if you're just doing a standard print-a-line-with-a-linefeed-at-the-end, echo is simpler. Thus, I'd replace the various printf "something\n" commands with echo "something", and printf "\nEnter the customers host URL:\n" with:
echo
echo "Enter the customers host URL:"
In the command
ssh "$customerurl" tail -f /data/jirastudio/jira/j2ee_*/log/main/current
(or ssh "$1" ... if you follow my recommendation about arguments instead of global variables), the wildcard (*) will be expanded on the local computer before being handed to ssh and passed to the remote computer to be executed. It'd be best to quote that argument to prevent that:
ssh "$customerurl" tail -f "/data/jirastudio/jira/j2ee_*/log/main/current"
Note that the quotes will be removed before it's passed to ssh and then to the remote computer, so they will not prevent the wildcard from being expanded on the remote computer.
The thing you're calling a URL isn't actually a URL; URLs are things like "https://stackoverflow.com/questions". They start with a protocol (or "scheme") like "http" or "ftp", then "://", then a server name, then "/", etc. ssh just takes a raw server name (optionally with a username, in the form user#server).
Update, based on EDIT 1: I wasn't clear on how to call the function; your definition (using mainmenu() { ...) is correct, but having defined the function you then need to actually run the function. Do to this, change the end of the script to something like this:
...
echo "Press 5 for Apache Error"
read -r -p "Pick a number: " mainmenuinput
mainmenu "$customerurl" "$mainmenuinput"
This will run the function, with the first argument ($1) set to "$customerurl", and second argument ($2) set to "$mainmenuinput".
There's also a problem with the elif clause you added in the function. The shell's syntax for test expressions is really really weird (mostly for historical reasons). Also, there are three common variants, the original [ ... ] (which is actually a command) which has the weirdest syntax, bash's [[ ... ]] variant (much cleaner syntax, but not available available in generic POSIX shells), and (( ... )) (cleaner syntax, math- rather than string-oriented, not portable). See BashFAQ #31 for details.
For what you're trying to do, any of these would work:
elif [ "$2" -gt 4 -o "$2" -lt 1 ]; then
# [ ... ] doesn't use || or &&, and uses -lt etc for numeric comparisons.
# < and > do string comparisons, which are ... different. And you'd
# need to quote them to keep them from being mistaken for redirects.
# Also, you need to specify the "$2" explicitly for each comparison.
elif [[ "$2" -gt 4 || "$2" -lt 1 ]]; then
# [[ ... ]] uses || and &&, but still uses -lt etc for numeric comparisons.
# < and > still do string comparisons, but don't need to be quoted
elif (( $2 > 4 || $2 < 1 )); then
# All numeric here, so < and > work
But there's still a problem, since the user might have entered something that isn't a number at all (just pressed return, typed "wibble", etc.), and in all of these cases numeric comparison will fail. Solution: skip the test, and use else instead of elif:
...
elif [ "$2" = "4" ]; then
ssh "$1" tail -f "/data/jirastudio/apache/logs/access_log"
else
echo "Uh uh uh, you didnt say the magic word! The number you picked isnt in the list. Pick again."
fi
}
... that way, if any of the previous conditions aren't met for any reason at all, it'll print the error message.
I'm trying to compare 2 strings. One comes from a file through the grep command and the other one never changes because I'm always comparing it with the ones I create while reading file texts. If they are equal, the program should print the data associated with the content that the new string contains. I've tried with all the syntax that bash allows (cause I'm new at bash) but it is just not working like I expected. It looks like the second if doesn't work, because I tried earlier without that and only print the strings (echo $text) and it worked, but not the proper way as the exercise I'm doing asks for. I have to show in the console only the pid and state of the processes that are running.
cd
cd /proc
run="State: S (sleeping)"
for i in $( ls -d */);
do
cd $i
if [ -f /proc/$i/status ];
then text="`grep -w "S" status`"
if [ "$text" == "$run" ]
then grep -w "Pid" status
grep -w "State" status
fi
cd /proc
else cd /proc
fi
done
;;
Your run variable contains State:<space>S (sleeping), but /proc/<pid>/status files contain State:<tab>S (sleeping) (at least, on my system). So you should replace that space character with tab character.
I was looking at an answer in another thread about which bracket pair to use with if in a bash script. [[ is less surprising and has more features such as pattern matching (=~) whereas [ and test are built-in and POSIX compliant making them portable.
Recently, I was attempting to test the result of a grep command and it was failing with [: too many arguments. I was using [. But, when I switched to [[ it worked. How would I do such a test with [ in order to maintain the portability?
This is the test that failed:
#!/bin/bash
cat > slew_pattern << EOF
g -x"$
EOF
if [ $(grep -E -f slew_pattern /etc/sysconfig/ntpd) ]; then
echo "slew mode"
else
echo "not slew mode"
fi
And the test that succeeded:
#!/bin/bash
cat > slew_pattern << EOF
g -x"$
EOF
if [[ $(grep -E -f slew_pattern /etc/sysconfig/ntpd) ]]; then
echo "slew mode"
else
echo "not slew mode"
fi
if [ $(grep -E -f slew_pattern /etc/sysconfig/ntpd) ]; then
This command will certainly fail for multiple matches. It will throw an error as the grep output is being split on line ending.
Multiple matches of grep are separated by new line and the test command becomes like:
[ match1 match2 match3 ... ]
which doesn't make much of a sense. You will get different error messages as the number of matches returned by grep (i.e the number of arguments for test command [).
For example:
2 matches will give you unary operator expected error
3 matches will give you binary operator expected error and
more than 3 matches will give you too many arguments error or such, in Bash.
You need to quote variables inside [ to prevent word splitting.
On the other hand, the Bash specific [[ prevents word splitting by default. Thus the grep output doesn't get split on new line and remains a single string which is a valid argument for the test command.
So the solution is to look only at the exit status of grep:
if grep -E -f slew_pattern /etc/sysconfig/ntpd; then
Or use quote when capturing output:
if [ "$(grep -E -f slew_pattern /etc/sysconfig/ntpd)" ]; then
Note:
You don't really need to capture the output here, simply looking at the exit status will suffice.
Additionally, you can suppress output of grep command to be printed with -q option and errors with -s option.
I'm writing a shell script to parse through log file and pull out all instances where sudo succeeded and/or failed. I'm realizing now that this probably would've been easier with shell's equivalent of regex, but I didn't want to take the time to dig around (and now I'm paying the price). Anyway:
sudobool=0
sudoCount=0
for i in `cat /var/log/auth.log`;
do
for word in $i;
do
if $word == "sudo:"
then
echo "sudo found"
sudobool=1;
sudoCount=`expr $sudoCount + 1`;
fi
done
sudobool=0;
done
echo "There were " $sudoCount " attempts to use sudo, " $sudoFailCount " of which failed."
So, my understanding of the code I've written: read auth.log and split it up line by line, which are stored in i. Each word in i is checked to see if it is sudo:, if it is, we flip the bool and increment. Once we've finished parsing the line, reset the bool and move to the next line.
However, judging by my output, the shell is trying to execute the individual words of the log file, typically returning '$word : not found'.
why don't you use grep for this?
grep sudo /var/log/auth.log
if you want a count pipe it to wc -l
grep sudo /var/log/auth.log | wc -l
or still better use -c option to grep, which prints how many lines were found containing sudo
grep -c sudo /var/log/auth.log
or maybe I am missing something simple here?
EDIT: I saw $sudoFailCount after scrolling, do you want to count how many failed attempts were made to use sudo ?? You have not defined any value for $sudoFailCount in your script, so it will print nothing. Also you are missing the test brackets [[ ]] around your if condition checking
Expanding on Sudhi's answer, here's a one-liner:
$ echo "There were $(grep -c ' sudo: ' /var/log/auth.log) attempts to use sudo, $(grep -c ' sudo: .*authentication failure' /var/log/auth.log) of which failed."
There were 17 attempts to use sudo, 1 of which failed.
Your error message arises from a lack of syntax in your if statement: you need to put the condition in [[brackets]]
Using the pattern matching in bash:
#!/bin/bash
sudoCount=0
while read line; do
sudoBool=0
if [[ "$line" = *sudo:* ]]; then
sudoBool=1
(( sudoCount++ ))
# do something with sudobool ?
fi
done < /var/log/auth.log
echo "There were $sudoCount attempts to use sudo."
I'm not initimately familiar with the auth.log -- what is the pattern to determine success or failure?