I'm a shell script newbie, so I must be doing something stupid, why won't this work:
#!/bin/sh
myFile=$1
while read line
do
ssh $USER#$line <<ENDSSH
ls -d foo* | wc -l
count=`ls -d foo* | wc -l`
echo $count
ENDSSH
done <$myfile
Two lines should be printed, and each should have the same value... but they don't. The first print statement [the result of ls -d foo* | wc -l] has the correct value, the second print statement is incorrect, it always prints blank. Do I need to do something special to assign the value to $count?
What am I doing wrong?
Thanks
#!/bin/sh
while read line; do
echo Begin $line
ssh $USER#$line << \ENDSSH
ls -d foo* | wc -l
count=`ls -d foo* | wc -l`
echo $count
ENDSSH
done < $1
The only problem with your script was that when the heredoc token is not quoted, the shell does variable expansion, so $count was being expanded by your local shell before the remote commands were shipped off...
Related
I'm trying to write a script that builds a list of nodes then ssh into the first node of that list
and runs a checknodes.sh script which it's self is just a for i loop that calls checknode.sh
The first 2 lines seems to work ok, the list builds successfully, but then I get either get just the echo line of checknodes.sh to print out or an error saying cat: gpcnodes.txt: No such file or directory
MYSCRIPT.sh:
#gets the master node for the job
MASTERNODE=`qstat -t -u \* | grep $1 | awk '{print$8}' | cut -d'#' -f 2 | cut -d'.' -f 1 | sed -e 's/$/.com/' | head -n 1`
#builds list of nodes in job
ssh -qt $MASTERNODE "qstat -t -u \* | grep $1 | awk '{print$8}' | cut -d'#' -f 2 | cut -d'.' -f 1 | sed -e 's/$/.com/' > /users/issues/slow_job_starts/gpcnodes.txt"
ssh -qt $MASTERNODE cd /users/issues/slow_job_starts/
ssh -qt $MASTERNODE /users/issues/slow_job_starts/checknodes.sh
checknodes.sh
for i in `cat gpcnodes.txt `
do
echo "### $i ###"
ssh -qt $i /users/issues/slow_job_starts/checknode.sh
done
checknode.sh
str=`hostname`
cd /tmp
time perf record qhost >/dev/null 2>&1 | sed -e 's/^/${str}/'
perf report --pretty=raw | grep % | head -20 | grep -c kernel.kallsyms | sed -e "s/^/`hostname`:/"
When ssh -qt $MASTERNODE cd /users/issues/slow_job_starts/ is finished, the changed directory is lost.
With the backquotes replaced by $(..) (not an error here, but get used to it), the script would be something like
for i in $(cat /users/issues/slow_job_starts/gpcnodes.txt)
do
echo "### $i ###"
ssh -nqt $i /users/issues/slow_job_starts/checknode.sh
done
or better
while read -r i; do
echo "### $i ###"
ssh -nqt $i /users/issues/slow_job_starts/checknode.sh
done < /users/issues/slow_job_starts/gpcnodes.txt
Perhaps you would also like to change your last script (start with cd /users/issues/slow_job_starts)
You will find more problems, like sed -e 's/^/${str}/' (the ${str} inside single quotes won't be replaced by a host), but this should get you started.
EDIT:
I added option -n to the ssh call.
Redirects stdin from /dev/null (actually, prevents reading from stdin).
Without this option only one node is checked.
I have to print number of folders in my directory, so i use
ls -l $1| grep "^d" | wc -l
after that, I would liked to add a text in the same line.
any ideas?
If you don’t want to use a variable to hold the output you can use echo and put your command in $( ) on that echo line.
echo $(ls -l $1| grep "^d" | wc -l ) more text to follow here
Assign the result to a variable, then print the variable on the same line as the directory name.
folders=$(ls -l "$1" | grep "^d" | wc -l)
printf "%s %d\n" "$1" "$folders"
Also, remember to quote your variables, otherwise your script won't work when filenames contain whitespace.
I searched SO but could not find any relevant post with this specific problem. I would like to know how to call a shell script which is stored in a variable of another shell script.
In the below script I am trying to read service name & corresponding shellscript, check if the service is running, if not, start the service using the shell script associated with that service name. tried multiple options shared in various forums(like 'eval' etc) with no luck. please help to provide your suggestions on this.
checker.sh
#!/bin/sh
while read service
do
servicename=`echo $service | cut -d: -f1`
servicestartcommand=`echo $service | rev | cut -d: -f1 | rev`
if (( $(ps -ef | grep -v grep | grep $servicename | wc -l) > 0 ))
then
echo "$servicename Running"
else
echo "!!$servicename!! Not Running, calling $servicestartcommand"
eval "$servicestartcommand"
fi
done < names.txt
Names.txt
WebSphere:\opt\software\WebSphere\startServer.sh
WebLogic:\opt\software\WebLogic\startWeblogic.sh
Your script can be refactored into this:
#!/bin/bash
while IFS=: read -r servicename servicestartcommand; do
if ps cax | grep -q "$servicename"; then
echo "$servicename Running"
else
echo "!!$servicename!! Not Running, calling $servicestartcommand"
$servicestartcommand
fi
done < names.txt
No need to use wc -l after grep's output as you can use grep -q
No need to use read full line and then use cut, rev etc later. You can use IFS=: and read the line into 2 separate variables
No need to use eval in the end
It is much simpler than you expect. Instead of:
eval "$servicestartcommand"
eval should only be used in extreme circumstances. All you need is
$servicestartcommand
Note: no quotes.
As an example, try this on the command-line:
cmd='ls -l'
$cmd
That should work. But:
"$cmd"
will fail. It will look for a program with a space in its name called 'ls -l'.
May be I don't get the idea, but why not use system variables?
export FOO=bar
echo $FOO
bar
given an array of pids and the code:
for i in ${listedPids[#]}
do
runningCheck="ps -u $USER | grep $i"
grepRes=(${runningCheck})
if [[ -n $grepRes ]]
then
echo $grepRes
echo $runningCheck
... code not related to the issue
fi
done
Regardless if those pids are active or not; I keep getting 'ps' from echo $grepRes while the output of echo $runningCheck shows up with the correct user name and pid. What am I missing?
Replace
"ps -u $USER | grep $i"
by
$(ps -u $USER | grep $i)
Command Substitution: Bash performs the expansion by executing your command and replacing the command substitution with the standard output of the
command, with any trailing newlines deleted.
I simplified your script and here's what it should look like.
for i in "${listedPids[#]}"
do
grepRes=$(ps --no-heading -p $i)
if [[ -n "$grepRes" ]]
then
echo "$grepRes"
... code not related to the issue
fi
done
An even shorter code could be written using while loop.
ps --noheading -p "${listedPids[#]}" | while read grepRes
do
echo "$grepRes"
... code not related to the issue
done
As alvits and l0b0 pointed out, I made a few syntax errors: grepRes=(${runningCheck}) when I just wanted to execute that line and not turn it to a list, and the fact pipes and redirects don't work in variables. In the end pgrep did the job as I just needed to continue looping till all the background processes ended.
Maybe you could try eval.
runningCheck1="ps -u $USER"
runningCheck2=" | grep $i"
echo $runningCheck1$runningCheck
eval $runningCheck1$runningCheck2
I find that a piece of my bash script causes the hang up. I extract it here :
#!/bin/bash
cat << EndOfFspreadFile >> ./myscript.sh
echo Enter Source Path :
read SRCPATH
FILECNT=`find $SRCPATH/* 2>/dev/null | wc -l`
FILECNTERR=`find $SRCPATH/* 2>&1 | grep "find:" | wc -l`
echo count : $FILECNT
echo problems : $FILECNTERR
EndOfFspreadFile
echo done
This script is expected to just append the script part in the integrated block into myscript.sh file. But it just HANGS !
Thanks !
- Mohamed -
Your $ variables and back quotes will get expanded. You need to escape them in script.
Right now you end up searching the entire filesystem.
Basically, find $SRCPATH/* 2>/dev/null | wc -l gets executed as find /* 2>/dev/null | wc -l
Here is how you can rewrite it (just one line example):
FILECNT=\$(find \$SRCPATH/* 2>/dev/null | wc -l)
By the way, it's easy to find out if you run bash -x <your script>.