I don't understand why this bash script won't work on BusyBox v1.29.3 () built-in shell (ash).
Here's the code:
#!/bin/sh
MODE=$(cat /etc/config/wireless | grep 'option mode') #not working
#MODE="option mode 'sta'" ==> this works
echo $MODE
MCHECK="option mode 'sta'"
echo $MCHECK
if [ "$MCHECK" = "$MODE" ];then
ping -c3 www.google.com > /dev/null
a=$?
echo $a
if [ $a -eq 0 ];then
echo "ok"
else
echo "fail"
fi
else
echo "no sta mode"
fi
It works correctly if I "force" the string with a variable.( the #MODE)
I imagine there are some characters in the cat returned variable that create a different string.
I always got "no sta mode" so the if won't return true.
The option mode in etc/config/wireless is the same as the string to compare.
Cannot find what am I missing..?
The problem was following gives a string with leading zeros.
MODE="$(cat /etc/config/wireless | grep 'option mode')"
Following gives the same result without leading spaces.
MODE="$(cat /etc/config/wireless | sed -n 's/\s*\(option mode.*\)/\1/p'"
Related
I have written a script to check process is running or not,it work fine but while testing it, i have found that it not include top command count running in other terminal
check-process.sh
#!/bin/sh
OK=1
CRITICAL=0
PROCESS_NUM=$( ps -ef | grep $1 | grep -v "grep "|grep -v "sh"|wc -l )
#echo $PROCESS_NUM
if [ $PROCESS_NUM = $OK ]
then
echo "OK"
elif [ $PROCESS_NUM = $CRITICAL ]
then
echo "CRITICAL"
elif [ $PROCESS_NUM > $OK ]
then
echo "MULTIPLE process are runing"
else
echo "error"
fi
And i run top command in two terminals and run this script as follow:
./check-process.sh top
and out put is 0 CRITICAL , but when i run normal command ps -ef |grep -v "grep "| wc -l it gives two counts.
That mess of greps just has to go.
One "trick" for finding processes by name without finding your grep is to use a regular expression. That is, after all, what the Global Regular Expression Print command is for. You can use parameter expansion to construct a safe regular expression based on your input string, perhaps like this:
#!/bin/sh
if [ -z "$1" ]; then
echo "I'd love me an option." >&2
exit 1
fi
OK=1
CRITICAL=0
x="${1#?}" # make a temporary string missing the 1st chararcter,
re="[${1%$x}]$x" # then place the 1st character within square brackets.
PROC_COUNT=$( ps -ef | grep -w -c "$re" ) # yay, just one pipe.
if [ "$PROC_COUNT" -eq "$OK" ]; then
echo "OK"
elif [ "$PROC_COUNT" -eq "$CRITICAL" ]; then
echo "CRITICAL"
elif [ "$PROC_COUNT" -gt "$OK" ]; then
echo "MULTIPLE process are running"
else
echo "error"
fi
There are a few notable changes here:
I added something to fail with better explanation if no option is given.
The pipeline, of course. And the lines that create $re.
We're using -gt and -eq to test numeric values. man test for details.
I renamed your count variable to be clearer. What is a "PROCESS_NUM" really? Sounds like a PID to me.
All variables are quoted. I don't need to tell you why, you have the Google.
That said, you should also consider using pgrep instead of any sort of counting pipe, if it's available on your system. Try running pgrep and see what your OS tells you.
I am looking to create a shell script to read the message log and when finds the correct string perform an action. So far I have the following:
#!/bin/bash
string="ntp engine ready"
tail -n 0 -f /var/log/messages | \
while read LINE
do
echo "$LINE | grep -q $string"
if [ $? == 0];then
shttpclient "http://127.0.0.1/do/action"
fi
done
But, I get the following error:
grep: engine: No such file or directory
grep: ready: No such file or directory
Even when I see the logger has outputted ntp engine ready.
Firstly, you need to fix your quotes:
echo "$LINE" | grep -q "$string"
Secondly, you can simply do:
if echo "$LINE" | grep -q "$string"; then
rather than checking the return code $? manually. Remember that [ is a command too and if is just checking its return code.
If you do need to use [, remember that ] is an argument to the command so it is essential to surround it with spaces:
if [ $? = 0 ]
I have also removed the second = as it is a bash extension to support it. Actually you are doing an integer comparison, so really it should be one of the following:
if [ $? -eq 0 ] # POSIX compliant
if (( $? == 0 )) # bash arithmetic context
Alter the line as follows:
echo "$LINE" | grep -q "$string"
The quotes were not set correctly. Like when you execute that: grep -q ntp engine ready; ntp is the string to search and engine and ready are the files. It must look like: grep -q "ntp engine ready".
I am trying to do the following in bash:
get my external IP
read first line of a file
compare both values
if it is not the same, delete the file and recreate it with the current address
I really don't know why this fails, all my script does is to output my current address and the first line of the file (which by the way is simply "asd" for testing)
#!/bin/bash
IP= curl http://ipecho.net/plain
OLD= head -n 1 /Users/emse/Downloads/IP/IP.txt
if [ "$IP" = "$OLD" ]; then
exit
else
rm /Users/emse/Downloads/IP/IP.txt
$IP> /Users/emse/Downloads/IP/IP.txt
exit
fi
Some obvious problems in your script:
Don't put spaces on either side of equal sign if you want to do assignment
You want the output of curl, head so wrap them in backticks (`)
You want to write $IP into the file, not to execute the content of it as a command, so echo it
The script becomes:
#!/bin/bash
IP=`curl http://ipecho.net/plain`
OLD=`head -n 1 /Users/emse/Downloads/IP/IP.txt`
if [ "$IP" = "$OLD" ]; then
exit
else
rm /Users/emse/Downloads/IP/IP.txt
echo $IP > /Users/emse/Downloads/IP/IP.txt
exit
fi
Excellent answer qingbo, just a tad bit of refinement:
#!/bin/bash
IP=`curl http://ipecho.net/plain`
OLD=`head -n 1 /Users/emse/Downloads/IP/IP.txt`
if [ "$IP" != "$OLD" ]; then
echo $IP > /Users/emse/Downloads/IP/IP.txt # > creates/truncates/replaces IP.txt
fi
I am writing a script that will take in 3 outputs and then search all files within a predefined path. However, my grep command seems to be breaking the script with error code 123. I have been staring at it for a while and cannot really seem the error so I was hoping someone could point out my error. Here is the code:
#! /bin/bash -e
#Check if path exists
if [ -z $ARCHIVE ]; then
echo "ARCHIVE NOT SET, PLEASE SET TO PROCEED."
echo "EXITING...."
exit 1
elif [ $# -ne 3 ]; then
echo "Illegal number of arguments"
echo "Please enter the date in yyyy mm dd"
echo "EXITING..."
exit 1
fi
filename=output.txt
#Simple signal handler
signal_handler()
{
echo ""
echo "Process killed or interrupted"
echo "Cleaning up files..."
rm -f out
echo "Finsihed"
exit 1
}
trap 'signal_handler' KILL
trap 'signal_handler' TERM
trap 'signal_handler' INT
echo "line 32"
echo $1 $2 $3
#Search for the TimeStamp field and replace the / and : characters
find $ARCHIVE | xargs grep -l "TimeStamp: $2/$3/$1"
echo "line 35"
fileSize=`wc -c out.txt | cut -f 1 -d ' '`
echo $fileSize
if [ $fileSize -ge 1 ]; then
echo "no"
xargs -n1 basename < $filename
else
echo "NO FILES EXIST"
fi
I added the echo's to know where it was breaking. My program prints out line 32 and the args but never line 35. When I check the exit code I get 123.
Thanks!
Notes:
ARCHIVE is set to a test directory, i.e. /home/'uname'/testDir
$1 $2 $3 == yyyy mm dd (ie a date)
In testDir there are N number of directories. Inside these directories there are data files that have contain data as well as a time tag. The time tag is of the following format: TimeStamp: 02/02/2004 at 20:38:01
The scripts goal is to find all files that have the date tag you are searching for.
Here's a simpler test case that demonstrates your problem:
#!/bin/bash -e
echo "This prints"
true | xargs false
echo "This does not"
The snippet exits with code 123.
The problem is that xargs exits with code 123 if any command fails. When xargs exits with non-zero status, -e causes the script to exit.
The quickest fix is to use || true to effectively ignore xargs' status:
#!/bin/bash -e
echo "This prints"
true | xargs false || true
echo "This now prints too"
The better fix is to not rely on -e, since this option is misleading and unpredictable.
xargs makes the error code 123 when grep returns a nonzero code even just once. Since you're using -e (#!/bin/bash -e), bash would exit the script when one of its commands return a nonzero exit code. Not using -e would allow your code to continue. Just disabling it on that part can be a solution too:
set +e ## Disable
find "$ARCHIVE" | xargs grep -l "TimeStamp: $2/$1/$3" ## If one of the files doesn't match the pattern, `grep` would return a nonzero code.
set -e ## Enable again.
Consider placing your variables around quotes to prevent word splitting as well like "$ARCHIVE".
-d '\n' may also be required if one of your files' filename contain spaces.
find "$ARCHIVE" | xargs -d '\n' grep -l "TimeStamp: $2/$1/$3"
I have been busy this week trying to wrap my head around a little Bash program to migrate a CMS from one server to another. The reasopn for this is because I have more tha 40 of these to do, and need to get it done in a timely manner, thus the Bash idea.
Needless to say, I have run into a couple of problems so far, but one of them has halted my development completetly, directory checking.
No I have tried a couple of methods and none of them seem to work really. The catch is that I have to check the folder on a remote server via ssh. Here my example:
ExSshRsa=~/.ssh/id_rsa
ExSshPort=22
ExSshHost=localhost
ExRoot=/var/www/
echo -n "Verifying Root access $ExRoot..."
SSHRoot='ssh -i $ExSshRsa -p $ExSshPort $ExSshHost [ -d $ExRoot ] || exit 1 '
echo $SSHRoot
if [ "$SSHRoot" -eq 0 ]
then
echo "OK"
else
echo "FAIL"
fi
I get the Error: [: : integer expression expected
Does the [ or test not resturn a 0 which is numerical. ?
Passing strings as arguments to a remote host is not trivial; you need to use arrays. A test example:
declare -a cmd=(touch "file name with spaces")
printf -v escaped_cmd_str '%q ' "${cmd[#]}"
ssh localhost $escaped_cmd
ssh localhost ls # Should return "file name with spaces" on a separate line
So your case should be:
ExSshRsa=~/.ssh/id_rsa
ExSshPort=22
ExSshHost=localhost
ExRoot=/var/www/
echo -n "Verifying Root access $ExRoot..."
declare -a cmd=( '[' -d "$ExRoot" ']' ) # Need to quote "[" since it's a Bash-specific symbol
printf -v escaped_cmd_str '%q ' "${cmd[#]}"
if ssh -i "$ExSshRsa" -p "$ExSshPort" "$ExSshHost" $escaped_cmd
then
echo "OK"
else
echo "FAIL"
fi
This is a rare case where using unquoted variable expansion is perfectly fine.
change the shebang to #!/bin/bash -x and look at the output...
you are storing a string in variable SSHRoot using single quotes, meaning that no variables will be expanded, i.e. a $ is still a $. Use double quotes instead, i.e. "
to store the output from a command in bash, use
var=$(cmd)
the exist status of a command is stored in the variable $?. Do a check on that after the ssh-command
you are never executing the ssh-command in your code
Great link here for bash-programming
Try the following:
ExSshRsa=~/.ssh/id_rsa
ExSshPort=22
ExSshHost=localhost
ExRoot=/var/www/
echo -n "Verifying Root access $ExRoot..."
cmd="bash -c \"[ -d $ExRoot ] || exit 1\""
SSHRoot="ssh -i $ExSshRsa -p $ExSshPort $ExSshHost ${cmd}"
$SSHRoot
if [ $? -eq 0 ]
then
echo "OK"
else
echo "FAIL"
fi
The variables weren't being replaced in your SSHRoot variable as it's in single quotes. Also, you weren't passing an executable command, so that's why I use bash -c above. It will run the bash commands inside the quoted string.
$? stores the exit value of the last command, in this case the SSHRoot one.
#!/bin/bash
ExSshRsa=~/.ssh/id_rsa
ExSshPort=22
ExSshHost=localhost
ExBase='/tmp/'
ExRoot='one space/'
declare -a AExRoot
for argR in "${ExRoot[#]}"
do
ExRoot+=($(printf %q "$argR"))
done
clear
FRoot=( $ExBase${ExRoot[#]} )
echo -n "Verifying Root access $FRoot..."
SSHRootTest="bash -c \"[ -d $FRoot ] && echo 0 && exit 0 || echo 1 && exit 1\""
SSHRoot=$( ssh -i $ExSshRsa -p $ExSshPort $ExSshHost ${SSHRootTest})
if [ $? -eq 0 ]
then
echo -en "\e[1;32mOK\e[0;37;m..."
else
echo -en "\e[1;31mFAIL\e[0;37;m..."
fi
sleep 1
if [ -w $FRoot ]
then
echo -e "\e[1;32mwritable\e[0;37;m"
else
echo -e "\e[1;31mNOT writeable\e[0;37;m"
fi
echo -e "\e[0;m"
exit 0
So I have incorporated all of the suggestions so far and have one last problem, the FRoot is not getting populated by the complete array values. Other than that I think it now has the subjective approach as suggested #john-keyes, the proper expansion #frederik and the crazy space escapes #l0b0