I want to write a shell script. I list my jpg files inside nested subdirectories with the following command line:
find . -type f -name "*.jpg"
How can I save the output of this command inside a variable and write a for loop for that? (I want to do some processing steps for each jpg file)
You don't want to store output containing multiple files into a variable/array and then post-process it later. You can just do those actions on the files on-the-run.
Assuming you have bash shell available, you could write a small script as
#!/usr/bin/env bash
# ^^^^ bash shell needed over any POSIX shell because
# of the need to use process-substitution <()
while IFS= read -r -d '' image; do
printf '%s\n' "$image"
# Your other actions can be done here
done < <(find . -type f -name "*.jpg" -print0)
The -print0 option writes filenames with a null byte terminator, which is then subsequently read using the read command. This will ensure the file names containing special characters are handled without choking on them.
Better than storing in a variable, use this :
find . -type f -name "*.jpg" -exec command {} \;
Even, if you want, command can be a full bloated shell script.
A demo is better than an explanation, no ? Copy paste the whole lines in a terminal :
cat<<'EOF' >/tmp/test
#!/bin/bash
echo "I play with $1 and I can replay with $1, even 3 times: $1"
EOF
chmod +x /tmp/test
find . -type f -name "*.jpg" -exec /tmp/test {} \;
Edit: new demo (from new questions from comments)
find . -type f -name "*.jpg" | head -n 10 | xargs -n1 command
(this another solution doesn't take care of filenames with newlines or spaces)
This one take care :
#!/bin/bash
shopt -s globstar
count=0
for file in **/*.jpg; do
if ((++count < 10)); then
echo "process file $file number $count"
else
break
fi
done
Related
I have the following 2 scripts, that recursively convert folders of images to pdf's for my wifes japanese manga kindle using find and Imagemagick convert:
#!/bin/bash
_d="$(pwd)"
echo "$_d"
find . -type d -exec echo "Will convert in the following order: {}" \;
find . -type d -exec echo "Converting: '{}'" \; -exec convert '{}/*.jpg' "$_d/{}.pdf" \;
and the same for PNG
#!/bin/bash
_d="$(pwd)"
echo "$_d"
find . -type d -exec echo "Will convert in the following order: {}" \;
find . -type d -exec echo "Converting: '{}'" \; -exec convert '{}/*.png' "$_d/{}.pdf" \;
Unfortunately I am not able make one universal script that works for all image formats.
How do I make one script that works for both ?
I would also need JPG,PNG as well as jpeg,JPEG
Thx in advance
I wouldn't use find at all, just a loop:
#!/use/bin/env bash
# enable recursive globs
shopt -s globstar
for dir in **/*/; do
printf "Converting jpgs in %s\n" "$dir"
convert "$dir"/*.jpg "$dir/out.pdf"
done
If you want to combine .jpg and .JPG in the same pdf, add nocaseglob to the shopt line. Add .jpeg to the mix? Add extglob and change "$dir"/*.jpg to "$dir"/*.#(jpg|jpeg)
You can do more complicated actions if you turn the find exec into a bash function (or even a standalone script).
#!/bin/bash
do_convert()(
shopt -s nullglob
for dir in "$#"; do
files=("$dir"/*.{jpg,JPG,PNG,jpeg,JPEG})
if [[ -z $files ]]; then
echo 1>&2 "no suitable files in $dir"
continue
fi
echo "Converting $dir"
convert "${files[#]}" "$dir.pdf"
done
)
export -f do_convert
pwd
echo "Will convert in the following order:"
find . -type d
# find . -type d -exec bash -c 'do_convert {}' \;
find . -type d -exec bash -c 'do_convert "$#"' -- {} \+
nullglob makes *.xyz return nothing if there is no match, instead of returning the original string unchanged
p/*.{a,b,c} expands into p/*.a p/*.b p/*.c before the * are expanded
x()(...) instead of the more normal x(){...} uses a subshell so we don't have to remember to unset nullglob again or clean up any variable definitions
export -f x makes function x available in subshells
we skip conversion if there are no suitable files
with the slightly more complicated find command, we can reduce the number of invocations of bash (probably doesn't save a great deal in this particular case)
how about a one-liner
dry-run
find -name \*.jpg -or -name \*.png | xargs -I xxx echo "xxx =>" xxx.pdf
run
find -name \*.jpg -or -name \*.png | xargs -I xxx echo xxx xxx.pdf
help
-name match name
-or logical or => both jpg and png
xargs map input into a name to execute a command on
-I select a name, it is like {} in file
NOTE
instead of $(pwd) which is a command substitution you can use variable $PWD
xxx maps into a name and xxx.pdf still has the matched extension found by find. which means filename.png becomes filename.png.pdf. If this is not desired, you can sed it
to run convert command in parallel you can use -P 0 with xargs -- see xargs --help
With sed to remove extensions
dry-run
find -name \*.jpg -or -name \*.png | sed 's/.\(png\|jpg\)$//g' | xargs -I xxx echo "xxx =>" xxx.pdf
#shawn Your solution works, just as I stated in the comments, I am to stupid to name the resulting pdf properly (folder name) and save in the script caller directory. Nevertheless, it solves my case insensitive jpg, jpeg, png problems just fine.
Here is shawns solution:
#!/bin/bash
# enable recursive globs
shopt -s globstar nocaseglob extglob
for dir in **/*/; do
printf "Converting (jpg|jpeg|png) in %s\n" "$dir"
convert "$dir"/*.#(jpg|jpeg|png) "$dir/out.pdf"
done
#jhnc Your solution works out of the box, it does exactly what I intended, and I really like calling functions, or even standalone scripts to increase complexity. One drawback is, that I can not Ctrl-c the process, because it is thereby threaded, or runs in a subshell ? I think you were missing an exit statement at the end of the function, it never stopped.
#!/bin/bash
do_convert()(
shopt -s nullglob
for dir in "$#"; do
files=("$dir"/*.{jpg,JPG,png,PNG,jpeg,JPEG})
if [[ -z $files ]]; then
echo 1>&2 "no suitable files in $dir"
continue
fi
echo "Converting $dir"
convert "${files[#]}" "$dir.pdf"
done
exit
)
export -f do_convert
pwd
echo "Will convert in the following order:"
find . -type d
# find . -type d -exec bash -c 'do_convert {}' \;
find . -type d -exec bash -c 'do_convert "$#"' -- {} \+
# everyone else, it's already after midnight again, I guess this is a trivial question for you guys, and I am very grateful for your ALL your answers, I didn't have the time to try everything.
I find linux bash very challenging.
A lot of ways to skin this cat. My thought is:
for F in `find . -type f -print`
do
TYPE=`file -n --mime-type $F`
if [ "$TYPE" = image/png ]
then
## do png conversion here
elif [ "$TYPE" = image/jpg ]
then
## do jpg conversion here
fi
done
I'm trying to write a bash script to copy all .desktop files under /nix/store to ~/.local/share/applications/. I'm not particular good with bash, so I would like assistance. I used the find command to find all files. Now I'm trying to create an array from the output with the help of readarray:
files=$(find /nix/store -type f -name \*.desktop)
echo $files
x=$(readarray -d 's' <<<$files)
echo $x
The echo $files will print the result of the find command, however the echo $x prints an empty line.
#!/usr/bin/env bash
files=$(find /nix/store -type f -name \*.desktop)
readarray array <<<$files
for i in ${array[#]}; do
cp $i ~/.loca/share/applications/
done
or
find /nix/store -type f -name \*.desktop -exec cp {} ~/.local/share/applications/ \;
Copying all .desktop files to ~/.local/share/applications/
find /nix/store -type f -name '*.desktop' \
-exec cp -v {} ~/.local/share/applications/ ';'
however the echo $x prints an empty line.
readarray produces no output. Instead, it stores the lines in the argument, which represents the name of the variable, the name of the array.
readarray -d 's' <<<$files
# ^^^ - stores output in array named s
printf "%s\n" "${s[#]}" # you can print the array s
If I'm not wrong and /nix/store/ is a regular directory, this should work:
cp /nix/store/*.desktop ~/.local/share/applications/
I want to prepend text to the name of every file of a certain type - in this case .txt files - located in the current directory or a sub-directory.
I have tried:
find -L . -type f -name "*.txt" -exec mv "{}" "PrependedTextHere{}" \;
The problem with this is dealing with the ./ part of the path that comes with the {} reference.
Any help or alternative approaches appreciated.
You can do something like this
find -L . -type f -name "*.txt" -exec bash -c 'echo "$0" "${0%/*}/PrependedTextHere${0##*/}"' {} \;
Where
bash -c '...' executes the command
$0 is the first argument passed in, in this case {} -- the full filename
${0%/*} removes everything including and after the last / in the filename
${0##*/} removes everything before and including the last / in the filename
Replace the echo with a mv once you're satisfied it's working.
Are you just trying to move the files to a new file name that has Prepend before it?
for F in *.txt; do mv "$F" Prepend"$F"; done
Or do you want it to handle subdirectories and prepend between the directory and file name:
dir1/PrependA.txt
dir2/PrependB.txt
Here's a quick shot at it. Let me know if it helps.
for file in $(find -L . -type f -name "*.txt")
do
parent=$(echo $file | sed "s=\(.*/\).*=\1=")
name=$(echo $file | sed "s=.*/\(.*\)=\1=")
mv "$file" "${parent}PrependedTextHere${name}"
done
This ought to work, as long file names does not have new line character(s). In such case make the find to use -print0 and IFS to have null.
#!/bin/sh
IFS='
'
for I in $(find -L . -name '*.txt' -print); do
echo mv "$I" "${I%/*}/prepend-${I##*/}"
done
p.s. Remove the echo to make the script effective, it's there to avoid accidental breakage for people who randomly copy paste stuff from here to their shell.
The following command attempts to enumerate all *.txt files in the current directory and process them one by one:
for line in "find . -iname '*.txt'"; do
echo $line
ls -l $line;
done
Why do I get the following error?:
ls: invalid option -- 'e'
Try `ls --help' for more information.
Here is a better way to loop over files as it handles spaces and newlines in file names:
#!/bin/bash
find . -type f -iname "*.txt" -print0 | while IFS= read -r -d $'\0' line; do
echo "$line"
ls -l "$line"
done
The for-loop will iterate over each (space separated) entry on the provided string.
You do not actually execute the find command, but provide it is as string (which gets iterated by the for-loop).
Instead of the double quotes use either backticks or $():
for line in $(find . -iname '*.txt'); do
echo "$line"
ls -l "$line"
done
Furthermore, if your file paths/names contains spaces this method fails (since the for-loop iterates over space separated entries). Instead it is better to use the method described in dogbanes answer.
To clarify your error:
As said, for line in "find . -iname '*.txt'"; iterates over all space separated entries, which are:
find
.
-iname
'*.txt' (I think...)
The first two do not result in an error (besides the undesired behavior), but the third is problematic as it executes:
ls -l -iname
A lot of (bash) commands can combine single character options, so -iname is the same as -i -n -a -m -e. And voila: your invalid option -- 'e' error!
More compact version working with spaces and newlines in the file name:
find . -iname '*.txt' -exec sh -c 'echo "{}" ; ls -l "{}"' \;
Use command substitution instead of quotes to execute find instead of passing the command as a string:
for line in $(find . -iname '*.txt'); do
echo $line
ls -l $line;
done
I'm trying to build a script that lists all the zip files in a set of directories, with some filters and get it to spit them out to file but when a filename has a space in it it seems to appear on a new line.
This list will eventually be used as an input to tar to gzip all the zip files, script is below:
#!/bin/bash
rm -f set1.txt
rm -f set2.txt
for line in $(find /home -type d -name assets ;);
do
echo $line >> set1.txt
for line in $(find $line -type f -name \*.zip -mtime +2 ;);
do
echo \"$line\" >> set2.txt
done;
This works as expected until you get a space in a filename then set2.txt contains entries like this:
"/home/xxxxxx/oldwebroot/htdocs/upload/assets/jobbags/rbjbCost"
"in"
"use"
"sept"
"2010.zip"
Does anyone know how I can get it to keep these filenames with spaces in in a single line with the whole lot wrapped in one set of quotes?
Thanks!
The correct way to loop over a set of files located via find is with a while read construct, thus:
while IFS= read -r -d '' line ; do
echo "$line" >> set1.txt
while IFS= read -r -d '' file ; do
printf '"%s"\n' "$file" >> set2.txt
done < <(find "$line" -type f -name \*.zip -mtime +2 -print0)
done < <(find /home -type d -name assets -print0)
For clarity I have given the inner loop variable a different name.
If you didn't have bash you'd have to issue the find command separately and redirect the output to a file, then read the file with while read ; do .. done < filename.
Note that each expansion of each variable is double-quoted. This is necessary.
Note also, however, that for what you want you can simply use the -printf switch to find, if you have GNU find.
find /home -type f -path '*/assets/*.zip' -mtime +2 -printf '"%p"\n' > set2.txt
Although, as #sarnold notes, this is not safe.
You should probably be executing your tar(1) command through some other mechanism; the find(1) program supports a -print0 option to request ASCII NUL-separated filename output, and the xargs(1) program supports a -0 option to tell it that the input is separated by ASCII NUL characters. (Since NUL is the only character that is not allowed in filenames, this is the only way to get reliable filename handling.)
Simply using the -print0 and -0 options will help but this still leaves the script open to another problem -- xargs(1) might decide to execute the tar(1) command two, three, or more times, depending upon its input. The last execution is the one that will "win", and the data from earlier invocations will be lost for ever. (This is useless as a backup.)
So you should also look into adding the --concatenate command line option to tar(1), too, so that it will add to the archive. It might make sense to perform the compression after all the files have been added, via gzip(1) or bzip2(1). (This does mean you need to remove the archive before a "fresh run" of this script.)