Doing an assignment for class that needs to be done using commands in the terminal. I have a shell file (temp1.sh) created in the home directory, and a shell file (temp2.sh) created in a folder (randomFolder). When I run temp2.sh I need to display the amount of characters in temp1.sh. I need to use the pipe command to accomplish this.
So I figure I need to change directory to the home directory then open the file temp1.sh and use thewc -c command to display the characters. I have been trying many different ways to execute this task and somehow can't get it to work. Any help would be appreciated. Without using a pipe I can get it to work, but I can't seem to write out this command line properly while using a pipe.
What I have done so far:
cd ~
touch temp1.sh
chmod 755 temp1.sh
echo 'This file has other commands that are not relevant and work' >> temp1.sh
mkdir randomFolder
cd randomFolder
touch temp2.sh
chmod 755 temp2.sh
echo cd ~ | wc -c temp1.sh >> temp2.sh
This last line tells me there is no such file "temp1.sh" after I run it. if I redirect to home then type wc -c temp1.sh, I get the desired output. I want this output to happen when I run temp2.sh.
Example without using pipe command:
echo wc -c ~/temp1.sh >> temp2.sh
This gives me the desired output when I run temp2.sh. However I need to accomplish this while using the pipe command.
Your code is close to working. The first part is fine:
cd ~
touch temp1.sh
chmod 755 temp1.sh
echo 'This file has other commands that are not relevant and work' >> temp1.sh
mkdir randomFolder
cd randomFolder
touch temp2.sh
chmod 755 temp2.sh
All of that should work. You problem is this part:
echo cd ~ | wc -c temp1.sh >> temp2.sh
You need to separate the cd ~ from something that runs some command and pipes the output to wc, and get the whole lot stored in temp2.sh. That could be something like:
echo "cd $HOME" > temp2.sh
echo "cat temp1.sh | wc -c" >> temp2.sh
The key point here is using separate lines for the cd command and the wc command. Using > for the first command ensures that you don't have stray garbage from previous failed attempts in temp2.sh. You can achieve the same result in multiple ways, including:
echo "cd; cat temp1.sh | wc -c" > temp2.sh
echo "cd ~; while read -r line; do echo "$line"; done < temp1.sh | wc -c" > temp2.sh
And then, finally, you need to execute temp2.sh. You might use any of these, though some (which?) depend on how your PATH is set:
./temp2.sh
temp2.sh
sh temp2.sh
sh -x temp2.sh
$HOME/randomFolder/temp2.sh
~/randomFolder/temp2.sh
Related
I have this bash script:
#!/bin/bash
rm /etc/stress.txt
cat /dev/smd10 | tee /etc/stress.txt &
for ((i=0; i< 1000; i++))
do
echo -e "\nRun number: $i\n"
#wait untill module restart and bee ready for next restart
dmesg | grep ERROR
echo -e 'AT+CFUN=1,1\r\n' > /dev/smd10
echo -e "\nADB device booted successfully\n"
done
I want to restart module 1000 times using this script.
Module is like android device witch has linux inside it. But I use Windows.
AT+CFUN=1,1 - reset
When I push script, after every restart I need a command which will wait module and start up again and execute script 1000 times. Then I do pull in .txt file and save all output content.
Which command should I use?
I try commands like wait, sleep, watch, adb wait-for-device, ps aux | grep... Nothing works.
Can someone help me with this?
I find the solution. This is how my script actually looks:
#!/bin/bash
cat /dev/smd10 &
TEST=$(cat /etc/output.txt)
RESTART_TIMES=1000
if [[ $TEST != $RESTART_TIMES ]]
then
echo $((TEST+1)) > /etc/output.txt
dmesg
echo -e 'AT+CFUN=1,1\r\n' > /dev/smd10
fi
These are the steps that you need to do:
adb push /path/to/your/script /etc/init.d
cd /etc
cat outputfile.txt - make an output file and write inside file 0 ( echo 0 > output.txt )
cd init.d
ls - you should see rc5.d
cd .. then cd rc5.d - go inside
ln -s ../init.d/yourscript.sh S99yourscript.sh
ls - you should see S99yourscript.sh
cd .. return to init.d directory
chmod +x yourscript.sh - add permision to your script
./yourscript.sh
I'm a bash noob, and I am trying to set up a sort of "hot reload" functionality for a project I'm working on using inotifywait. Ubuntu 20.04 if that matters.
Here is what I hoped would have worked:
inotifywait -m -r ../.. -e modify,create,delete |
while read line; do
custom_command
done
I'm having two problems:
Issue #1 is that custom_command takes some time to work, and so if I make more changes to the directory in the meantime, custom command appears to "queue up" custom_command, where really I just want it to keep the most recent one and drop the others.
Issue #2 is that I'm getting some sort of "double output." So for example if I bash auto-exec.sh and auto-exec.sh looks like this:
inotifywait -m -r . -q -e modify,create,delete
Then each time a change registers, I get this as output (not a mistake that it's doubled -- I get two identical lines each time there is a modification):
./ MODIFY auto-exec-testfile.txt
./ MODIFY auto-exec-testfile.txt
I should note I've tried making changes both with Visual Code Studio and gedit, with the same results.
If I modify the bash file like so:
inotifywait -m -r . -q -e modify,create,delete |
while read line; do
echo "$line"
echo "..."
done
I get the following output each time there is a change:
./ MODIFY auto-exec-testfile.txt
...
./ MODIFY auto-exec-testfile.txt
...
If I modify bash_test.sh to the following:
inotifywait -m -r . -q -e modify,create,delete |
while read line; do
echo "help me..."
done
Then I get the following each time a change is made:
help me...
help me...
What happened to the the ./ MODIFY ... line?? Presumably there's something I don't understand about bash, stdout or similar /related concepts here?
And finally, if I change the .sh file to the following:
inotifywait -m -r . -q -q -e modify,create,delete |
while read _; do
echo "help me..."
done
Then I get no output at all. This one I think I understand, because the -q -q means that inotifywait is in "super silent" mode, so there is no log and therefore nothing to trigger the while.
What I'd love to do is just trigger the code once when something changes, and drop all but the most recent execution. I'm not sure doing this using a while is entirely necessary, but I tried inotifywait -m -r . -q -q -e modify,create,delete | echo "help me..", and the script printed "help me..." once at startup, then exited on modification.
Assistance very much appreciated.
EDIT - 20201-Mar-23
I removed -m and create from the inotifywait line, and it appears to work as expected, except that it doesn't stay "up" in monitor mode. So this at least only gives me one entry from inotifywait:
notifywait -r .. -q -e modify,delete |
while read line1; do
echo ${line1}
done
Related:
inotifywait - pause monitoring while executing command
https://unix.stackexchange.com/questions/140679/using-inotify-to-monitor-a-directory-but-not-working-100
inotifywait not performing the while loop in bash script
while inotifywait -e close_write,delete .; do
pkill custom_command
custom_command&
done
I have a bash script that puts a bunch of commands to make a directory into a text file. Then it cats the file into sh to run the commands. What I am trying to do is only run the command if the directory doesn't already exist.
Here is what I have:
A text file with something like this:
mkdir /path/to/a/directory
mkdir /path/to/another/directory
mkdir /path/to/yet/another/directory
In my script I have a line like this
cat /path/to/my/file.txt | sh
But is there a way to do something like this?
cat /path/to/my/file.txt | if path already exists then go to the next, if not | sh
In other words I would like to skip the attempt to make the directory if the path already exists.
Update: The OP has since clarified that use of mkdir is just an example, and that he needs a generic mechanism to conditionally execute lines from a text file containing shell commands, based on whether the commands refers to an existing directory or not:
while read -r cmd dir; do [[ -d $dir ]] || eval "$cmd $path"; done < /path/to/my/file.txt
The while loop reads the text file containing the shell commands line by line.
read -r cmd dir parses each line into the first token - assumed to be the command (mkdir in the sample input) - and the rest, assumed to be the directory path.
[[ -d $dir ]] tests the existence of the directory path, and || only executes its RHS if the test fails, i.e., if the directory does not exist.
eval "$cmd $path" then executes the line; note that use of eval here is not any less secure than piping to sh - in both cases you must trust the strings representing the commands. (Using eval from the current Bash shell means that Bash will execute the command, not sh, but I'm assuming that's not a problem.)
Original answer, based on the assumption that mkdir is actually used:
The simplest approach in your case is to add the -p option to your mkdir calls, which will quietly ignore attempts to create a directory that already exists:
mkdir -p /path/to/a/directory
mkdir -p /path/to/another/directory
mkdir -p /path/to/yet/another/directory
To put it differently: mkdir -p ensures existence of the target dir., whether that dir. already exists or has to be created.
(mkdir -p can still fail, such as when the target path is a file rather than a dir., or if you have insufficient permissions to create the dir.)
You can then simply pass the file to sh (no need for cat and a pipe, which is less efficient):
sh /path/to/my/file.txt
In case you do not control creation of the input file, you can use sed to insert the -p option:
sed 's/^mkdir /&-p /' /path/to/my/file.txt | sh
I'm not clear if you want to check for the existence of files or directories.. but here's how to to it:
Run your command if the file exists:
[ -f /path/to/my/file.txt ] && cat /path/to/my/file.txt | sh
or to check for directories:
[ -d /path/to/my/directory ] && cat /path/to/my/file.txt | sh
Write your own mkdir function.
Assuming your file doesn't use mkdir -p anywhere this should work.
mkdir() {
for dir; do
[ -d "$dir" ] || mkdir "$dir"
done
}
export -f mkdir
sh < file
I am trying to ls the directories and print them out but nothing is being displayed. I am able to SSH and execute the first pwd. However, anything within the the for loop has no output. I know for sure there are directories called event-test- because I've done so manually. I've manually entered the directory (/data/kafka/tmp/kafka-logs/) and ran this piece of code and the correct output appeared so I'm not sure why
manually entered has correct output:
for i in `ls | grep "event-test"`; do echo $i; done;
script:
for h in ${hosts[*]}; do
ssh -i trinity-prod-keypair.pem bc2-user#$h << EOF
sudo bash
cd /data/kafka/tmp/kafka-logs/
pwd
for i in `ls | grep "event-test-"`; do
pwd
echo $i;
done;
exit;
exit;
EOF
done
It is because
`ls | grep "event-test-"`
is executing on your localhost not on remote host. Besides parsing ls is error prone and not even needed. You can do:
for h in "${hosts[#]}"; do
ssh -t -t trinity-prod-keypair.pem bc2-user#$h <<'EOF'
sudo bash
cd /data/kafka/tmp/kafka-logs/
pwd
for i in *event-test-*; do
pwd
echo "$i"
done
exit
exit
EOF
done
When parsing ls it is good practice to do ls -1 to get a prettier list to parse. Additionally, when trying to find files named "event-test-" I would recommend the find command. Since I am not completely sure what you are attempting to do other than list the locations of these "event-test" files I'd recommend something more similar to the following:
for h in "${hosts[#]}"; do ssh trinity-prod-keypair.pem bc2-user#$h -t -t "find /data/kafka/tmp/kafka-logs/ -type f -name *event-test-*;" ; done
This will give you a pretty output of the full path to the file and the file name.
I hope this helps.
I'm building a little bash script to run another bash script that's found in multiple directories. Here's the code:
cd /home/mainuser/CaseStudies/
grep -R -o --include="Auto.sh" [\w] | wc -l
When I execute just that part, it finds the same file 5 times in each folder. So instead of getting 49 results, I get 245. I've written a recursive bash script before and I used it as a template for this problem:
grep -R -o --include=*.class [\w] | wc -l
This code has always worked perfectly, without any duplication. I've tried running the first code with and without the " ", I've tried -r as well. I've read through the bash documentation and I can't seem to find a way to prevent, or even why I'm getting, this duplication. Any thoughts on how to get around this?
As a separate, but related question, if I could launch Auto.sh inside of each directory so that the output of Auto.sh was dumped into that directory; without having to place Auto.sh in each folder. That would probably be much more efficient that what I'm currently doing and it would also probably fix my current duplication problem.
This is the code for Auto.sh:
#!/bin/bash
index=1
cd /home/mainuser/CaseStudies/
grep -R -o --include=*.class [\w] | wc -l
grep -R -o --include=*.class [\w] |awk '{print $3}' > out.txt
while read LINE; do
echo 'Path '$LINE > 'Outputs/ClassOut'$index'.txt'
javap -c $LINE >> 'Outputs/ClassOut'$index'.txt'
index=$((index+1))
done <out.txt
Preferably I would like to make it dump only the javap outputs for the application its currently looking at. Since those .class files could be in any number of sub-directories, I'm not sure how to make them all dump in the top folder, without executing a modified Auto.sh in the top directory of each application.
Ok, so to fix the multiple find:
grep -R -o --include="Auto.sh" [\w] | wc -l
Should be:
grep -R -l --include=Auto.sh '\w' | wc -l
The reason this was happening, was that it was looking for instances of the letter w in Auto.sh. Which occurred 5 times in the file.
However, the overall fix that doesn't require having to place Auto.sh in every directory, is something like this:
MAIN_DIR=/home/mainuser/CaseStudies/
cd $MAIN_DIR
ls -d */ > DirectoryList.txt
while read LINE; do
cd $LINE
mkdir ProjectOutputs
bash /home/mainuser/Auto.sh
cd $MAIN_DIR
done <DirectoryList.txt
That calls this Auto.sh code:
index=1
grep -R -o --include=*.class '\w' | wc -l
grep -R -o --include=*.class '\w' | awk '{print $3}' > ProjectOutputs.txt
while read LINE; do
echo 'Path '$LINE > 'ProjectOutputs/ClassOut'$index'.txt'
javap -c $LINE >> 'ProjectOutputs/ClassOut'$index'.txt'
index=$((index+1))
done <ProjectOutputs.txt
Thanks again for everyone's help!