Assume you have a file called “heading” as follows
echo "Permissions^V<TAB>^V<TAB>Size^V<TAB>^V<TAB>File Name" > heading
echo "-------------------------------------------------------" >> heading
Write a (single) set of commands that will create a report as follows:
make a list of the names, permissions and size of all the files in your current directory,
matching (roughly) the format of the heading you just created,
put the list of files directly following the heading, and
save it all into a file called “file.list”.
All this is to be done without destroying the heading file.
I need to be able to do this all in a pipleline without altering the file. I can't seem to do this without destroying the file. Can somebody please make a pipe for me?
You can use command group:
{ cat heading; ls -l | sed 's/:/^V<tab>^V<tab>/g'; } > file.list
Related
root#VM-0-11-debian:~/linux/2023/01# ls
root#VM-0-11-debian:~/linux/2023/01# ls > list
root#VM-0-11-debian:~/linux/2023/01# ls
list
root#VM-0-11-debian:~/linux/2023/01# cat list
list
I know that > will redirect stdout to file. it will create the file if not present, otherwise replace it.
I would like to ask that is the shell command ls > list implementation process as I described below?
1)As the file named list not exists, so create a file named list first.
2)ls command will list the directory content(list). the content listed(list) will be in the standard output.
3)Add the content of the standard output(list) to the file named list in a replaced way.
My personal understanding of the implementation process as described above, I hope you can give me some guidance. Thank you.
The file redirection operator > is handled by your shell and any file to which you write will be created/truncated before the binary is started. That's why you can see the file name list in the content of the file: the file has already been created before the ls process was started.
So yes, your understanding is correct.
This is why it is not possible to do something like sort txt > txt – the file txt will be truncated before sort reads it. You will end up with an empty file.
I am trying to rename all files located in a directory (recursively) with a specific meta data field appended to the end of the png file name.
the meta data field name is "aesthetic_score" with a value range from 1.0-9.0
when I type:
exiftool -Aesthetic_score -G1 -s testn.png
the result is:
[PNG] Aesthetic_score : 7.0
This is how I would like to append the png files recursively within a directory.
Note i would like to swap out the word aesthetic with the word chad in the append, and not all files will have this data field:
input file:
filename001.png (metadata aesthetic_score:7.0)
output:
filename001-chad-score-70.png
I tried to use Digikam and JExifToolGui-2.01, without success.
I am trying to perform this task in the cmd line, although other solutions are welcome. Thank you for your help.
So, this might work for you, I can't really test it; note that you would need to get rid of the echo before the mv for it to actually do something (rename rather than just show what it would do).
while read name
do
newname=$(exiftool -G1 -s "$name"|awk '$2~/FileName/{name=$4}; $2~/Aesthetic_score/{basename=gensub(/^(.+)\....$/,"\\1","1",name);ext=gensub(/^.*\.(...)$/,"\\1","1",name);gsub(/\./,"",$4);print basename"."$4"."ext}')
echo mv "$name" "$newname"
done <<<$( find -iname \*.png )
Basically the find at the very end finds all the pngs.
The while loop takes every name find throws it, and passes each file through exiftool (using your specs) and parses the output using awk, which then outputs the new name, which gets captured in the shell variable by the same name.
And finally the mv (without the echo) renames the files.
I made a shell script the purpose of which is to find files that don't contain a particular string, then display the first line that isn't empty or otherwise useless. My script works well in the console, but for some reason when I try to direct the output to a .txt file, it comes out empty.
Here's my script:
#!/bin/bash
# takes user input.
echo "Input substance:"
read substance
echo "Listing media without $substance:"
cd media
# finds names of files that don't feature the substance given, then puts them inside an array.
searchresult=($(grep -L "$substance" *))
# iterates the array and prints the first line of each - contains both the number and the medium name.
# however, some files start with "Microorganisms" and the actual number and name feature after several empty lines
# the script checks for that occurence - and prints the first line that doesnt match these criteria.
for i in "${searchresult[#]}"
do
grep -m 1 -v "Microorganisms\|^$" $i
done >> output.txt
I've tried moving the >>output.txt to right after the grep line inside the loop, tried switching >> to > and 2>&1, tried using tee. No go.
I'm honestly feeling utterly stuck as to what the issue could be. I'm sure there's something I'm missing, but I'm nowhere near good enough with this to notice. I would very much appreciate any help.
EDIT: Added files to better illustrate what I'm working with. Sample inputs I tried: Glucose, Yeast extract, Agar. Link to files [140kB] - the folder was unzipped beforehand.
The script was given full permissions to execute. I don't think the output is being rewritten because even if I don't iterate and just run a single line of the loop, the file is empty.
So I need to create a lot of text files.
Each of the text file is named AAAAA.txt, BBBBB.txt, CCCCC.txt and etc etc.
Within each text file, all the content is as follows:
1.Copy "to-be-replaced".txt into the folder EXCLUSIVE.
2.Copy the gs file to replace the existing gs file.
3.The .projectdata should also be copied to the correct path.
So, I need to write a script, that copies the name of the file (AAAAA, BBBBB, and so on) and then place it in the "to-be-replaced" within its content.
How can I do that? need some idea please.
Thank you~~
MT32
Use a HERE document which expands variables if the delimiter isn't quoted:
#!/bin/bash
for char in {A..Z} ; do
filename=$char$char$char$char$char.txt
cat <<EOF > $filename
1.Copy $filename into the folder EXCLUSIVE.
2.Copy the gs file to replace the existing gs file.
3.The .projectdata should also be copied to the correct path.
EOF
done
I'm trying to redirect(?) my standard error/output to a text file.
I did my research, but for some reason the online answers are not working for me.
What am I doing wrong?
cd /home/user1/lists/
for dir in $(ls)
do
(
echo | $dir > /root/user1/$dir" "log.txt
) > /root/Desktop/Logs/Update.log
done
I also tried
2> /root/Desktop/Logs/Update.log
1> /root/Desktop/Logs/Update.log
&> /root/Desktop/Logs/Update.log
None of these work for me :(
Help please!
Try this for the basics:
echo hello >> log.txt 2>&1
Could be read as: echo the word hello, redirecting and appending STDOUT to the file log.txt. STDERR (file descriptor 2) is redirected to wherever STDOUT is being pointed. Note that STDOUT is the default and thus there is no "1" in front of the ">>". Works on the current line only.
To redirect and append all output and error of all commands in a script, put this line near the top. It will be in effect for the length of the script instead of doing it on each line:
exec >>log.txt 2>&1
If you are trying to obtain a list of the files in /home/user1/lists, you do not need a loop at all:
ls /home/usr1/lists/ >Update.log
If you are attempting to run every file in the directory as an executable with a newline as its input, and collect the output from all these programs in Update.log, try this:
for file in /home/user1/lists/*; do
echo | "$file"
done >Update.log
(Notice how we avoid the useless use of ls and how there is no redirection inside the loop.)
If you want to create an empty file called *.log.txt for each file in the directory, you would do
for file in /home/user1/lists/*; do
touch "$(basename "$file")"log.txt
done
(Using basename to obtain the file name without the directory part avoids the cd but you could do it the other way around. Generally, we tend to avoid changing the directory in scripts, so that the tool can be run from anywhere and generate output in the current directory.)
If you want to create a file containing a single newline, regardless of whether it already exists or not,
for file in /home/user1/lists/*; do
echo >"$(basename "$file")"log.txt
done
In your original program, you redirect the echo inside the loop, which means that the redirection after done will not receive any output at all, so the created file will be empty.
These are somewhat wild guesses at what you might actually be trying to accomplish, but should hopefully help nudge you slightly in the right direction. (This should properly be a comment, I suppose, but it's way too long and complex.)