I am copying some specific lines from one file to another.
grep '^stringmatch' /path/sfile-*.cfg >> /path/nfile-*.cfg
Here what's happening: its creating a new file called nfile-*.cfg and copying those lines in that. The file names sfile- * and nfile- * are randomly generated and are generally followed by a number. Both sfile-* and nfile-* are existing files and there is only one such file in the same directory. Only the number that follows is randomly generated. The numbers following in sfile and nfile need not be same. The files are not created simultaneously but are generated when a specific command is given. But some lines from one file to the another file needs to be appended.
I'm guessing you actually want something like
for f in /path/sfile-*.cfg; do
grep '^stringmatch' "$f" >"/path/nfile-${f#/path/sfile-}"
done
This will loop over all sfile matches and create an nfile target file with the same number after the dash as the corresponding source sfile. (The parameter substitution ${variable#prefix} returns the value of variable with any leading match on the pattern prefix removed.)
If there is only one matching file, the loop will only run once. If there are no matches on the wildcard, the loop will still run once unless you enable nullglob, which changes the shell's globbing behavior so that wildcards with no matches expand into nothing, instead of to the wildcard expression itself. If you don't want to enable nullglob, a common workaround is to add this inside the loop, before the grep;
test -e "$f" || break
If you want the loop to only process the first match if there are several, add break on a line by itself before the done.
If I interpret your question correctly, you want to output to an existing nfile, which has a random number in it, but instead the shell is creating a file with an asterisk in it, so literally nfile-*.cfg.
This is happening because the nfile doesn't exist when you first run the command. If the file doesn't exist, bash will fail to expand nfile-*.cfg and will instead use the * as a literal character. This is correct behaviour in bash.
So, it looks like the problem is that the nfile doesn't exist when you start your grep. You'll need to create one.
I'll leave code to others, but I hope the explanation is useful.
Related
I have some files named in a specifc pattern, for example, ab_2000_1.jpg. In this name 2000 is representing years and 1 representing month(1 means january). I have a 20 years of monthly files like this.
Now I want to rename every one of them into the following format ab_2000_1_12.jpg, ab_2000_2_12.jpg, etc
I know how to rename files using rename and sed command. But I want to know how can I loop this command for all files.
Any help is highly appreciated.
You can use a for loop to loop over all file names matching a pattern as for file in pattern; do some_commands; done.
You don't need sed to modify the file name in this case. A variable substitution like ${variable%pattern} will remove the shortest string matching pattern from the end of the variable value.
The following example code will remove .jpg from the end of the file name and append _12.jpg to the result.
for file in ab_*_*.jpg
do
mv "$file" "${file%.jpg}_12.jpg"
done
I have a folder that was created automatically. The user unintentionally provided smart (curly) quotes as part of the name, and the process that sanitizes the inputs did not catch these. As a result, the folder name contains the smart quotes. For example:
this-is-my-folder’s-name-“Bob”
I'm now trying to rename/remove said folder on the command line, and none of the standard tricks for dealing with files/folders with special characters (enclosing in quotes, escaping the characters, trying to rename it by inode, etc.) are working. All result in:
mv: cannot move this-is-my-folder’s-name-“Bob” to this-is-my-folders-name-BOB: No such file or directory
Can anyone provide some advice as to how I can achieve this?
To get the name in a format you can copy-and-paste into your shell:
printf '%q\n' this*
...will print out the filename in a manner the shell will accept as valid input. This might look something like:
$'this-is-my-folder200\231s-name-200\234Bob200\235'
...which you can then use as an argument to mv:
mv $'this-is-my-folder200\231s-name-200\234Bob200\235' this-is-my-folders-name-BOB
Incidentally, if your operating system works the same way mine does (when running the test above), this would explain why using single-character globs such as ? for those characters didn't work: They're actually more than one byte long each!
You can use shell globbing token ? to match any single character, so matching the smart quotes using ? should do:
mv this-is-my-folder?s-name-?Bob? new_name
Here replacing the smart quotes with ? to match the file name.
There are several possibilities.
If an initial substring of the file name ending before the first quote is unique within the directory, then you can use filename completion to help you type an appropriate command. Type "mv" (without the quotes) and the unique initial substring, then press the TAB key to request filename completion. Bash will complete the filename with the correct characters, correctly escaped.
Use a graphical file browser. Then you can select the file to rename by clicking on it. (Details of how to proceed from there depend on the browser.) If you don't have a graphical terminal and can't get one, then you may be able to do the same with a text-mode browser such as Midnight Commander.
A simple glob built with the ? or * wildcard should be able to match the filename
Use a more complex glob to select the filename, and perhaps others with the same problem. Maybe something like *[^a-zA-Z0-9-]* would do. Use a pattern substitution to assign a new name. Something like this:
for f in *[^a-zA-Z0-9-]*; do
mv "$f" "${f//[^a-zA-Z0-9-]/}"
done
The substitution replaces all appearances of a characters that are not decimal digits, appercase or lowercase Latin letters, or hyphens with nothing (i.e. it strips them). Do take care before you use this, though, to make sure you're not going to make more changes than you intend to do.
I would like to rename many files in this format
abc.123.fits
abcd.1234.fits
efg.12.fits
to this format
abc.fits
abcd.fits
efg.fits
I tried the rename function, but since the part I'm trying to replace is not the same in all files, it did not work. I am using Linux.
for f in *; do mv "$f" "${f%%.*}.${f##*.}"; done`
${f%%.*} removes everything after the first period, including the period. ${f##*.} removes everything before the last period, including the period (i.e. it gets the file extension). Concatenating these two, with a period between them, gives you the desired result.
You can change the * to a more restrictive pattern such as *.fits if you don't want to rename all files in the current directory. The quotes around the parameters to mv are necessary if any filenames contain whitespace.
Many other variable substitution expressions are available in bash; see a reference such as TLDP's Bash Parameter Substitution for more information.
When we use the redirect IO operator for a shell script does the operator keep all the data to be written in memory and write it all at once or does write it to file line by line.
Here is what i am working on.
I have about 200 small files ~1000 lines each in a specific format. I want to process (do a regex and change the format a little) each line in all the files and have the new transformed lines in a single combined file.
I have a transformscript.sh that takes a single file and applies the transformation. I run it in the following manner
sh transformscript.sh somefile.txt > newfile.txt
This works fine and fast for a single file.
How do i extend to do it for all the files. will it be efficient to change transformscript.sh to take a directory as argument instead of filename and add a for loop to transform all the lines of all the files together. Or should I run the above trnsformscript.sh for each file and create a new file for each one and combine then separately.
Thanks.
The redirect operator simply opens the file for writing and passes that file descriptor to the shell as its standard output. The shell then writes to the file directly.
You probably do NOT want to run the script separately for each file since you will incur the overhead of bash process creation for each pass. For example:
# don't do it this way
for somefile in $(ls somefiles*.txt); do
newfile=${somefile//some/new}
sh transformscript.sh $somefile > $newfile
done
The above starts one shell for every file found which is pretty inefficient. It would be better to rewrite transformscript.sh to handle multiple files if possible. Depending on how complicated your transform is and whether you need to keep the original filenames, you might be able to use a single sed process. For example, assume you have 200 files named test1.txt through test200.txt all with a "Hello world" line you want to change to "Hello joe". You could do something as simple a this:
sed -i.save 's/Hello world/Hello joe/' test*.txt
The -i tells sed to do an "in place" edit (edit the original file) and the optional ".save" argument to -i makes a backup copy of the original file with a .save extension before editing the original file. Note, this will leave the original contents in the .save files and the new content in the files with the original name which may not be what you want.
Alright, so I'm trying to combine some but not all of my script's parameters into one string. I'm trying to write a script that changes spaces in a file name to underscores, and when the option -r is given, it recursively does it to every file in the folder.
Assuming the file is saved as removespaces.sh, if you run removespaces.sh file with spaces.doc it doesn't really have to care about parameters, I can just use $*
but, when I'm trying to do it for an entire folder I now have -r as $1. So I can't just (be lazy) use $*.. how could I create a string that's equal to $2 to end?
A string of $2 to the end of the parameters:
"${*:2}"
This differs from "${#:2}" in that it concatenates all the arguments, with one space between each. In general, it is possible that neither form is what you want (if, for example, you have files with more than one consecutive space in their name).