There is a program that I run with command line. The output is a file. I have to run the program with various parameters so I always have to change the output filename (otherwise it will always be the same and the older will automatically be deleted) and run the program again and again. I tried :
./program param1 param2 > result1.txt
but not surprisingly
cat result1.txt
run the program. I need a command line that will automatically rename the output file at the end of the program.
I can not change the program code.
Thanks
You can enclose your line in another script that does something like:
PARAM_1="$1"
PARAM_2="$2"
CMD="./program"
$CMD $PARAM_1 $PARAM_2 > "result-${PARAM_1}-${PARAM_2}"
The scripts calls your command and redirects the output to a filename with a name that depends on the input parameters
This works with 2 parameters, but it can be easily generalised
UPDATE:
I just though of a different version that uses MD5 for the output filename, so that it will be consistent even with long, messy parameters and it's also valid for any number of params:
#!/bin/bash
HASH="$(echo "$#" | md5sum | cut -f1 -d' ')"
CMD="./program"
"$CMD" "$#" > "result-$HASH.txt"
Just rename the output filename using nanosecond date value as:
mv result.txt "result-$(date --rfc-3339=ns).txt"
at the end of your script.
Related
I want to have a command in a variable that runs a program and specifies the output filename for it depending on the number of files exits (to work on a new file each time).
Here is what I have:
export MY_COMMAND="myprogram -o ./dir/outfile-0.txt"
However I would like to make this outfile number increases each time MY_COMMAND is being executed. You may suppose myprogram creates the file soon enough before the next call. So the number can be retrieved from the number of files exists in the directory ./dir/. I do not have access to change myprogram itself or the use of MY_COMMAND.
Thanks in advance.
Given that you can't change myprogram — its -o option will always write to the file given on the command line, and assuming that something also out of your control is running MY_COMMAND so you can't change the way that MY_COMMAND gets called, you still have control of MY_COMMAND
For the rest of this answer I'm going to change the name MY_COMMAND to callprog mostly because it's easier to type.
You can define callprog as a variable as in your example export callprog="myprogram -o ./dir/outfile-0.txt", but you could instead write a shell script and name that callprog, and a shell script can do pretty much anything you want.
So, you have a directory full of outfile-<num>.txt files and you want to output to the next non-colliding outfile-<num+1>.txt.
Your shell script can get the numbers by listing the files, cutting out only the numbers, sorting them, then take the highest number.
If we have these files in dir:
outfile-0.txt
outfile-1.txt
outfile-5.txt
outfile-10.txt
ls -1 ./dir/outfile*.txt produces the list
./dir/outfile-0.txt
./dir/outfile-1.txt
./dir/outfile-10.txt
./dir/outfile-5.txt
(using outfile and .txt means this will work even if there are other files not name outfile)
Scrape out the number by piping it through the stream editor sed … capture the number and keep only that part:
ls -1 ./dir/outfile*.txt | sed -e 's:^.*dir/outfile-\([0-9][0-9]*\)\.txt$:\1:'
(I'm using colon : instead of the standard slash / so I don't have to escape the directory separator in dir/outfile)
Now you just need to pick the highest number. Sort the numbers and take the top
| sort -rn | head -1
Sorting with -n is numeric, not lexigraphic sorting, -r reverses so the highest number will be first, not last.
Putting it all together, this will list the files, edit the names keeping only the numeric part, sort, and get just the first entry. You want to assign that to a variable to work with it, so it is:
high=$(ls -1 ./dir/outfile*.txt | sed -e 's:^.*dir/outfile-\([0-9][0-9]*\)\.txt$:\1:' | sort -rn | head -1)
In the shell (I'm using bash) you can do math on that, $[high + 1] so if high is 10, the expression produces 11
You would use that as the numeric part of your filename.
The whole shell script then just needs to use that number in the filename. Here it is, with lines broken for better readability:
#!/bin/sh
high=$(ls -1 ./dir/outfile*.txt \
| sed -e 's:^.*dir/outfile-\([0-9][0-9]*\)\.txt$:\1:' \
| sort -rn | head -1)
echo "myprogram -o ./dir/outfile-$[high + 1].txt"
Of course you wouldn't echo myprogram, you'd just run it.
you could do this in a bash function under your .bashrc by using wc to get the number of files in the dir and then adding 1 to the result
yourfunction () {
dir=/path/to/dir
filenum=$(expr $(ls $dir | wc -w) + 1)
myprogram -o $dir/outfile-${filenum}.txt
}
this should get the number of files in $dir and append 1 to that number to get the number you need for the filename. if you place it in your .bashrc or under .bash_aliases and source .bashrc then it should work like any other shell command
You can try exporting a function for MY_COMMAND to run.
next_outfile () {
my_program -o ./dir/outfile-${_next_number}.txt
((_next_number ++ ))
}
export -f next_outfile
export MY_COMMAND="next_outfile" _next_number=0
This relies on a "private" global variable _next_number being initialized to 0 and not otherwise modified.
I'm using cat to create a new file via a shell script. It looks something like:
./script.sh > output.txt
How can I access output.txt as a variable in my script. I've tried $1 but that doesn't work.
The script looks something like:
#!/bin/sh
cat << EOF
echo "stuff"
EOF
Since there doesn't apear to be an os-agnostic way to do this, is there a way I pass the output into the script as an argument and then save the cat results to a file inside the script?
So the command would look like: ./script.sh output.txt and I can access the output as $1. Is something like this possible?
The Literal Question: Determining Where Your Stdout Was Redirected To
When a user runs:
./yourscript >outfile
...they're telling their shell to open outfile for write, and connect it to the stdout of your script, before starting your script. Consequently, all the operations on the filename are already finished when your script is started, so the name isn't passed to the script directly.
On Linux (only), you can access the location to which your stdout was redirected before your script was started through procfs:
output_dest=$(readlink -f /dev/fd/1)
echo "My output is being written to $output_dest"
This is literally interrogating where your first file descriptor (which is stdout) is open to. Note that the results won't always be useful -- if your program is being piped into something else, for instance, it might be something like [pipe: 12345].
If you care about portability or robustness, you should generally write your software in such a way that it doesn't need to know or care where its stdout is being directed.
The Best Practice: Redirecting Your Script's Stdout Yourself
Better practice, if you need an output filename that your script can access, is to accept that as an explicit argument:
#!/bin/sh
# ^^ note that that makes this a POSIX sh script, not a bash script
outfile=$1
exec >"$outfile" # all commands below here have their output written to outfile
cat >>EOF
This is written to $outfile
EOF
...and then directing the user to pass the filename as an argument:
./yourscript outfile
#!/bin/sh
outfile=$1
cat << EOF > "$outfile"
echo "stuff"
EOF
With
./script.sh output.txt
You write to the file output.txt
Setting a default value, in case the user doesn't pass an argument, is left for a different question.
I want to make a simple dmenu command that reads a file of commands and names. Then takes the names and displays them using dmenu then takes dmenu's output and runs the associated command using the file again.
I got to the point where dmenu displays the names, but I don't really know where to go from there. Learning bash is a really daunting task to me and I don't really know where to start with this seemingly simple script/command.
here is the file:
Pushbullet
google-chrome-stable --app=https://www.pushbullet.com
Steam
steam
Chrome
google-chrome-stable
Libre Office
libreoffice
Transmission
transmission-qt
Audio Control Panel
sudo pavucontrol & bluberry
and here is what I have so far for my command:
awk 'NR % 2 != 0' /home/rocco/programlist | dmenu | ??(grep -l "stdout" /home/rocco/programlist....)
It was my thinking that I could somehow pipe into grep or awk with the name of the application then get the line number then add one and pipe that into sh.
Thanks
I have no experience with dmenu but if I understand how it works correctly, this should do what you want. Wrapping a command in $(…) returns the output as a variable, which we can pass on to another command.
#!/bin/bash
plist="/home/rocco/programlist"
# pipe every second line to dmenu
selected=$(awk 'NR % 2 != 0' "$plist" | dmenu)
# search for the selected item, get the command after it
cmd=$(grep -A1 "$selected" "$plist" | tail -n 1)
# run the command
$cmd
Worth mentioning a mistake in your question. dmenu sends to stdout, or standard output, but the next program in line would be reading stdin, or standard input. In any case, grep can't take patterns on standard input, which is why I've saved to a variable instead of trying to pipe it somewhere.
Assuming you have programlist.txt in the working directory you can use:
awk 'NR%2 !=0' programlist.txt |dmenu |awk '{system("grep --no-group-separator -A 1 '"'"'"$0"'"'"' programlist.txt");}' |awk '{if(NR==2){system($0);}}'
Note the quoting of the $0 in the first awk envocation. This is necessary to get names with spaces in them like "Libre Office"
I run the following code for concatenating files in a directory given as the argument for the script file in bash
for i in $*
do
cat $* > /home/christy/Documents/filetest/catted.txt
done
This produce the error
cat: /home/christy/Documents/filetest/catted.txt: input file is output file
I think there are at least 4 things wrong with your script....
Firstly, your loop will set the value of i to the name of each file in succession, so you would want to actually use i inside your loop, like this:
for i in $*
cat "$i" ....somewhere
done
Secondly, if you use the > redirection, each file will land exactly on top of the previous one, so you should really use the >> redirection will append the current file to the end of the previous one like this
for i in $*
do
cat "$i" >> ...somewhere
done
Thirdly, I think you should use double-quoted "$#" to get all your command-line arguments, rather than plain $*
for i in "$#"
...
Fourthly, you can achieve the exact effect I think you want with this simpler command:
cat "$#" > /home/christy/Documents/filetest/catted.txt
You can't cat a file back onto itself. That's what "input file is output file" means. Because catted.txt shows up in your list of arguments to cat, it is going to try to cat to itself. So, move catted.txt to somewhere other than the source directory.
Let me first describe my situation, I am working on a Linux platform and have a collection of .bmp files that add one to the picture number from filename0022.bmp up to filename0680.bmp. So a total of 658 pictures. I want to be able to run each of these pictures through a .exe file that operates on the picture then kicks out the file to a file specified by the user, it also has some threshold arguments: lower, upper. So the typical call for the executable is:
./filter inputfile outputfile lower upper
Is there a way that I can loop this call over all the files just from the terminal or by creating some kind of bash script? My problem is similar to this: Execute a command over multiple files with a batch file but this time I am working in a Linux command line terminal.
You may be interested in looking into bash scripting.
You can execute commands in a for loop directly from the shell.
A simple loop to generate the numbers you specifically mentioned. For example, from the shell:
user#machine $ for i in {22..680} ; do
> echo "filename${i}.bmp"
> done
This will give you a list from filename22.bmp to filename680.bmp. That simply handles the iteration of the range you had mentioned. This doesn't cover zero padding numbers. To do this you can use printf. The printf syntax is printf format argument. We can use the $i variable from our previous loop as the argument and apply the %Wd format where W is the width. Prefixing the W placeholder will specify the character to use. Example:
user#machine $ for i in {22..680} ; do
> echo "filename$(printf '%04d' $i).bmp"
> done
In the above $() acts as a variable, executing commands to obtain the value opposed to a predefined value.
This should now give you the filenames you had specified. We can take that and apply it to the actual application:
user#machine $ for i in {22..680} ; do
> ./filter "filename$(printf '%04d' $i).bmp" lower upper
> done
This can be rewritten to form one line:
user#machine $ for i in {22..680} ; do ./filter "filename$(printf '%04d' $i).bmp" lower upper ; done
One thing to note from the question, .exe files are generally compiled in COFF format where linux expects an ELF format executable.
here is a simple example:
for i in {1..100}; do echo "Hello Linux Terminal"; done
to append to a file:(>> is used to append, you can also use > to overwrite)
for i in {1..100}; do echo "Hello Linux Terminal" >> file.txt; done
You can try something like this...
#! /bin/bash
for ((a=022; a <= 658 ; a++))
do
printf "./filter filename%04d.bmp outputfile lower upper" $a | "sh"
done
You can leverage xargs for iterating:
ls | xargs -i ./filter {} {}_out lower upper
Note:
{} corresponds to one line output from the pipe, here it's the inputfile name.
Output files wouldbe named with postfix '_out'.
You can test that AS-IS in your shell :
for i in *; do
echo "$i" | tr '[:lower:]' '[:upper:]'
done
If you have a special path, change * by your path + a glob : Ex :
for i in /home/me/*.exe; do ...
See http://mywiki.wooledge.org/glob
This while prepend the name of the output images like filtered_filename0055.bmp
for i in *; do
./filter $i filtered_$i lower upper
done