Not able to execute echo within legacy in Shell scripting - linux

Below is my code and I am able to get the ssh connection. But after that it is doing nothing.
log_time="date +%F\%T"
PR_ONE="username#hostname"
file="/home/log.txt"
to_list="myemail"
echo "`$log_time`" >> $file
`ssh $PR_ONE "echo df -hP | grep fs1 | awk '{print $4}'"` >> $file
cat $file | mailx -s "Disk space usages" $to_list
I am getting the email but only with $log_time. I know that I am doing something wrong in quotations in the ssh line.
I am new to shell scripting.

Try this :
echo "df -hP | grep fs1 | awk '{print $4}'" | ssh -tt $PR_ONE >> $file
or prefer this :
ssh -tt $PR_ONE << EOF >> $file
df -hP | grep fs1 | awk '{print $4}'
EOF

Related

escaping special character while executing commands remotely using ssh

When ran commands locally on the remote server outputs would work as expected:
desired_kernel_version="5.4.0-105-generic"
cat /tmp/grb.bkp | grep GRUB_DEFAULT
GRUB_DEFAULT=0
kernel_position=$(awk -F\' '$1=="menuentry " || $1=="submenu " {print i++ " : " $2}; /\tmenuentry / {print "\t" i-1">"j++ " : " $2};' /boot/grub/grub.cfg | grep "${desired_kernel_version}" | grep -v recovery | awk '{ print $1}' | sed 's/ //g')
echo $k_position
1>2
sed -i "s/GRUB_DEFAULT=0/GRUB_DEFAULT=\"${k_position}\"/g" /tmp/grb.bkp
cat /tmp/grb.bkp | grep GRUB_DEFAULT
GRUB_DEFAULT="1>2"
desired output when ran from remote server:
replace 0 of GRUB_DEFAULT value to kernel_position within quotes.
server=abcd
kernel_position=$(ssh -qT $server awk -F\' '$1=="menuentry " || $1=="submenu " {print i++ " : " $2}; /\tmenuentry / {print "\t" i-1">"j++ " : " $2};' /boot/grub/grub.cfg | grep "${desired_kernel_version}" | grep -v recovery | awk '{ print $1}' | sed 's/ //g')
ssh -qT $server "sed -i "s/GRUB_DEFAULT=0/GRUB_DEFAULT=\"${k_position}\"/g" /tmp/grb.bkp"
Suggesting to avoid quoting hell.
Send muli-line command into ssh by writing a script remote-script.sh with all lines.
remote-script.sh
#!/bin/bash
source ~/.bash_profile
$k_position=$1
desired_kernel_version="5.4.0-105-generic"
cat /tmp/grb.bkp | grep GRUB_DEFAULT
GRUB_DEFAULT=0
kernel_position=$(awk -F\' '$1=="menuentry " || $1=="submenu " {print i++ " : " $2}; /\tmenuentry / {print "\t" i-1">"j++ " : " $2};' /boot/grub/grub.cfg | grep "${desired_kernel_version}" | grep -v recovery | awk '{ print $1}' | sed 's/ //g')
echo $k_position
1>2
sed -i "s/GRUB_DEFAULT=0/GRUB_DEFAULT=\"${k_position}\"/g" /tmp/grb.bkp
cat /tmp/grb.bkp | grep GRUB_DEFAULT
GRUB_DEFAULT="1>2"
Give current user execution permissions on remote-script.sh
chmod u+x remote-script.sh
Use scp command to copy remote-script.sh to $server. If possible only once at deploy time.
scp -q remote-script.sh $server:/home/your-user
Use ssh command to run remote-script.sh on remote server. Pass $k_position in command line.
ssh -qT $server "bash -c /home/your-user/remote-script.sh $k_position"
BTW, in computing kernel_position, suggesting to fold all awk, grep, sed commands into a single awk script.

How to direct linux bash script output to one line per host

I'd like to change my script(s) so that the command output is separated by a comma and is all on one line per host. Any ideas on how I can achieve this:
1st Script:
#!/bin/bash
for i in `cat ~/hostnames.txt`
do
ssh -q $i 'bash -s' < server_info.sh
done
2nd Script (server_info.sh):
#!/bin/bash
echo -n "Name: "
uname -n
echo -n "CPUs: "
cat /proc/cpuinfo* | grep processor | wc -l
echo -n "Memory (kb): "
cat /proc/meminfo | grep MemTotal: | awk '{print $2}'
echo -n "Current Kernel: "
uname -a | awk '{print $3}'
echo -n "IP: "
hostname -i
echo -e
Changing your 1st script:
#!/bin/bash
for i in cat ~/hostnames.txt
do
ssh -q $i 'bash -s' < server_info.sh
done | awk -v RS= '{$1=$1}1'
Note: Your server_info.sh can be a lot more optimized.For example:
cat /proc/meminfo | grep MemTotal: | awk '{print $2}'
could be changed to:
awk '/MemTotal:/{print $2}' /proc/meminfo

Searching a specific file system in bash

I have a task which asks to write a script which displays all partitions formatted with a specific file system, given as parameter.
I have written the script but when i run it it displays '0'. What am i doing wrong?
This is my code:
#!/bin/bash
n=sudo parted -l | tail -n +8 | awk '{print $5}' | wc | awk '{print $2}'
m=sudo parted -l | tail -n +8 | awk '{print $5}'
q=sudo parted -l | tail -n +8
for i in $n; do
if [ "[ $m | sed -n ip ]" = "$1" ]; then
echo "$q | sed -n ip"
fi
done
Different approach from yours, but does it do what you need?
lsblk -f | awk '$0 ~ fs {print $NF}' fs=ext2

Custom grep file output

I'm running the command below:
for line in $(cat file1.txt); do cat file2.txt | grep ${line}; done
and it´s works fine..but I'm looking a way to print the results in a file like this:
$(line) - grep result
Is there a way to customize my grep output?
Thanks
file1="file1.txt";
file2="file2.txt";
for line in $file1; do
result=$(cat $file2 | grep $line | sed -e :a -e N -e '$!ba' -e 's/\n/ /g'));
echo "$line-$result";
done
if the result of $(cat file2.txt | grep $line) are multi lines, you should implement to echo with for statement.
for line in $(file1.txt); do
result=$(cat file2.txt | grep $line);
echo $line
for _line in $result; do
echo " -$_line";
done
done

How to sleep for 1 second between each xargs command?

For example, if I execute
ps aux | awk '{print $1}' | xargs -I {} echo {}
I want to let the shell sleep for 1 second between each echo.
How can I change my shell command?
You can use the following syntax:
ps aux | awk '{print $1}' | xargs -I % sh -c '{ echo %; sleep 1; }'
Be careful with spaces and semicolons though. After every command in between brackets, semicolon is required (even after the last one).
Replace echo by some shell script named sleepecho containing
#!/bin/sh
sleep 1
echo $*
If your awk supports it:
ps aux | awk '{ system("sleep 1"); print $1 }' | xargs -I {} echo {}q
or skip awk and xargs altogether
ps aux | while read -r user rest;
echo $user
sleep 1;
done

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