The following command below does not succeed.
for i in {1..5} ; do cat /etc/fstab | egrep "(ext3|ext4|xfs)" | awk '{print $2}' | cut -d"/" -f1-$i ; done
It seems that $i is ignored completely. It always returns instead result of
cut -d"/" -f1-
Any idea why it fails?
Thanks in advance!
The command itself is a part of a script that should help me to auto re-arrange fstab lines to match the right mount order (like /test/subfolder must come after /test was mounted and not before).
I tried and it didn't work for zsh shell. BUT I tried it in bash and it does work, so if you are using zsh just run the command with bash and it should work ;)
Related
I have bash script that use username and password as argument, so I what to delete that command from history,
I've tried to add:
history -d ${history 1 | awk '{print $1}'}
But I get:
${history 1 | awk '{print $1}'}: bad substitution
Then I tried:
history -d ${history 1 | awk '{print $1}'}
But nothig is happened.
I also try to wite the last command's number to another file and then cat
history -d $(cat tst.txt)
and also nothing happened...
Is there any suggestion for doing that?
Thanks a lot!
I can see two ways of achieving this.
your_script; history -d $(history 1)
unset HISTFILE; your_script; HISTFILE=~/.history
I'm developping a script to search for patterns within scripts executed from CRON on a bunch of remote servers through SSH.
Script on client machine -- SSH --> Remote Servers CRON/Scripts
For now I can't get the correct output.
Script on client machine
#!/bin/bash
server_list=( '172.x.x.x' '172.x.x.y' '172.x.x.z' )
for s in ${server_list[#]}; do
ssh -i /home/user/.ssh/my_key.rsa user#${s} crontab -l | grep -v '^#\|^[[:space:]]*$' | cut -d ' ' -f 6- | awk '{print $1}' | grep -v '^$\|^echo\|^find\|^PATH\|^/usr/bin\|^/bin/' | xargs -0 grep -in 'server.tld\|10.x.x.x'
done
This only gives me the paths of scripts from crontab, not the matched lines and line number plus the first line is prefixed with "grep:" keyword (example below):
grep: /opt/directory/script1.sh
/opt/directory/script2.sh
/opt/directory/script3.sh
/opt/directory/script4.sh
How to get proper output, meaning the script path plus line number plus line of matching pattern?
Remote CRON examples
OO 6 * * * /opt/directory/script1.sh foo
30 6 * * * /opt/directory/script2.sh bar
Remote script content examples
1 ) This will match grep pattern
#!/bin/bash
ping -c 4 server.tld && echo "server.tld ($1)"
2 ) This won't match grep pattern
#!/bin/bash
ping -c 4 8.x.x.x && echo "8.x.x.x ($1)"
Without example input, it's really hard to see what your script is attempting to do. But the cron parsing could almost certainly be simplified tremendously by refactoring all of it into a single Awk script. Here is a quick stab, with obviously no way to test.
#!/bin/sh
# No longer using an array for no good reason, so /bin/sh will work
for s in 172.x.x.x 172.x.x.y 172.x.x.z; do
ssh -i /home/user/.ssh/my_key.rsa "user#${s}" crontab -l |
awk '! /^#|^[[:space:]]*$/ && $6 !~ /^$|^(echo|find|PATH|\/usr\/bin|\/bin\/)/ { print $6 }' |
# no -0; use grep -E and properly quote literal dot
xargs grep -Ein 'server\.tld|10.x.x.x'
done
Your command would not output null-delimited data to xargs so probably the immediate problem was that xargs -0 would receive all the file names as a single file name which obviously does not exist, and you forgot to include the ": file not found" from the end of the error message.
The use of grep -E is a minor hack to enable a more modern regex syntax which is more similar to that in Awk, where you don't have to backslash the "or" pipe etc.
This script, like your original, runs grep on the local system where you run the SSH script. If you want to run the commands on the remote server, you will need to refactor to put the entire pipeline in single quotes or a here document:
for s in 172.x.x.x 172.x.x.y 172.x.x.z; do
ssh -i /home/user/.ssh/my_key.rsa "user#${s}" <<\________HERE
crontab -l |
awk '! /^#|^[[:space:]]*$/ && $6 !~ /^$|^(echo|find|PATH|\/usr\/bin|\/bin\/)/ { print $6 }' |
xargs grep -Ein 'server\.tld|10.x.x.x'
________HERE
done
The refactored script contains enough complexities in the quoting that you probably don't want to pass it as an argument to ssh, which requires you to figure out how to quote strings both locally and remotely. It's easier then to pass it as standard input, which obviously just gets transmitted verbatim.
If you get "Pseudo-terminal will not be allocated because stdin is not a terminal.", try using ssh -t. Sometimes you need to add multiple -t options to completely get rid of this message.
I have a problem with cat. I want to write script doing the same thing as ps -e. In pid.txt i have PID of running processes.
ls /proc/ | grep -o "[0-9]" | sort -h > pid.txt
Then i want use $line like a part of path to cmdline for evry PID.
cat pid.txt | while read line; do cat /proc/$line/cmdline; done
i try for loop too
for id in 'ls /proc/ | grep -o "[0-9]\+" | sort -h'; do
cat /proc/$id/cmdline;
done
Don't know what i'm doing wrong. Thanks in advance.
I think what you're after is this - there were a few flaws with all of your approaches (or did you really just want to look at process with a single-digit PID?):
for pid in $(ls /proc/ | grep -E '^[0-9]+$'|sort -h); do cat /proc/${pid}/cmdline; tr '\x00' '\n'; done
You seem to be in a different current directory when running cat pid.txt... command compared to when you ran your ls... command. Run both your commands on the same terminal window, or use absolute path, like /path/to/pid.txt
Other than your error, you might wanna remove -o from your grep command as it gives you 1 digit for a matching pid. For example, you get 2 when pid is 423. #Roadowl also pointed that already.
I want to have a single command, not a script, that I can use to define a variable as a command output and then put that output into other commands. My best guess as to what that would look like is this:
LIST=$(ls) | head -1 | echo "${LIST}"
One reason that I want to do this is so that I can create a command that can find the pid of a program and then kill that pid. My best try doing that is:
DiscPid=$(ps -e | grep Discord | cut -b 1-5 | head -1 \ ) | kill "${DiscPid}"
But I'm not able to get this to work
I'm still relatively new to Linux and Bash so any help would be appreciated
Use a semicolon after setting the variable: var=foo; echo $var
You don't need piping here
DiscPid=$(code) | kill "${DiscPid}"
Change '|' to ';' and this one '\' also spare
DiscPid=$(ps -e | grep Discord | cut -b 1-5 | head -1); kill "${DiscPid}"
I have been trying to learn more about Linux and have spent this morning focusing on the awk command. the command I have been trying to get to work is below.
ls -lRt lpftp.* | awk '{print $7, $9}' | mkdir -p $(awk '{print $1}') | ls -lRt lpftp.* | cp $(awk '{print $9, $7}')
Essentially I am trying to move each file in a directory into a sub directory based on that files last modified day. The command first prints only the files I want, then uses mkdir to create a folder based on the day of the month it was last modified. What I want to do after that is move each file into its associated directory, however as the command is now it moves every file into the 01 folder and prints out the following text
cp: 0653-436 12 is a directory.
Specify -r or -R to copy.
once for every directory.
does anyone know how I can fix this issue? or if there is a better way to go about it?
ls -lRt lpftp.* | awk '{print $7, $9}' | while read day file ; do mkdir -p "$day"; cp "$file" "$day"; done
The commands between do and done will be executed for each line of output, with the first thing awk prints in the day variable and the second in file (per line). I used quotes here somewhat unnecessarily, as there will not be spaces in the variables given the method by which they are set.
The safest way to do something like this -- and the fastest to execute -- is to use awk on the data to output a shell script. In awk, print the mkdir and cp commands you expect to execute. Pipe the results into head(1) until you're satisfied. Maybe look at the whole thing in less(1). Then execute as follows:
ls -lRg lpfpt.* | awk script.awk | sh -ex
That will echo the commands to standard error, and stop on the first error. If you're super absolutely sure it's right, drop the x option.
The advantage of this approach over a loop or a bunch of subprocesses in awk (with the system function) is:
you can see what's going to happen, and what's happening
speed of execution