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Im trying to learn some bash script writing and cleaning out some old CDs (remember those?)
What I have is a bunch of backup CDs with no rhyme or reason to them so I'd like to create a grep script that will search them based on keywords. (I'm currently trying to test the script first against the desktop) I know how to run grep, but its the scripting I'm having trouble with.
So here's what I have:
#!/bin/bash
#CDGrepScript
SOURCEDIR=/home/name/Desktop (I'm currently testing it with files on the desktop)
#mount /dev/cdrom
#SOURCEDIR=/dev/cdrom
echo "hello, $USER. I will search your files"
echo Begin Search...
grep -ir "taxes|personal|School" *
echo $results
echo "The search is complete. Goodbye"
exit
Now when I run this against files on the desktop. My script hangs after "Begin search" What am I doing wrong?
Thanks for the help
You might be served better by a more general tool. Like a rgrep (recursive grep) that will walk through a tree searching for a search term. An example:
# rgrep
#
# Search for text strings in a directory hierarchy
set +x
case $# in
0 | 1 )
# Not enough arguments -- give help message
echo "Usage: $0 search_text pathname..." >&2
exit 1
;;
* )
# Use the first argument as a search string
search_text=$1
shift
# Use the remaining argument(s) as path name(s)
find "$#" -type f -print |
while read pathname
do
egrep -i "$search_text" $pathname /dev/null
done
;;
esac
Put this in your path, then you just change directories to the mount point for the CD-ROM, and type
$ rgrep "taxes" .
Or whatever other search you wish to perform.
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I 've got tree of folders like:
00 -- 0
-- 1
...
-- 9
...
99 -- 0
-- 1
...
-- 9
How is the simplest way to create in every single subfolders a file like:
/00/0/00_0.txt
and save to every files some kind of data?
I tried with touch and with loop but without success.
Any ideas how to make it very simple?
List all directories using globs. Modify the listed paths with sed so that 37/4 becomes 37/4/37_4.txt. Use touch to create empty files for all modified paths.
touch $(printf %s\\n */*/ | sed -E 's|(.*)/(.*)/|&\1_\2.txt|')
This works even if 12/3 was just a placeholder and your actual paths are something like abcdef/123. However it will fail when your paths contain any special symbols like whitespaces, *, or ?.
To handle arbitrary path names use the following command. It even supports linebreaks in path names.
mapfile -td '' a < <(printf %s\\0 */*/ | sed -Ez 's|(.*)/(.*)/|&\1_\2.txt|')
touch "${a[#]}"
You may use find and then run commands using -exec
find . -type d -maxdepth 2 -mindepth 2 -exec bash -c 'f={};
cmd=$(echo "${f}/${f%/*}_${f##*/}.txt"); touch $cmd' \;
the bash substitution ${f%/*}_${f##*/} replaces the last / with _
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Let's assume I have a group of files "aab.md", "aac.md", "aad.md" ... "csdw.md". Content/filenames are actually in (non-latin) utf-8. They can be sorted alphabetically.
How can I get in Bash a subset of those files starting with e.g. "aad.md" and upwards?
declare -a files
while IFS= read -r -d $'\0' file; do
filename=${file##*/}
if [[ ! "$filename" < "aad.md" ]]
then
files=("${files[#]}" "$file")
fi
done < <(find . -name "*.md" -print0)
The array "${files[#]}" should now contain paths to files whose basename is greater than aad.md.
This uses a number of less well-known techniques in bash: arrays, prefix substitution, zero-terminated records (and their reading), and process substitution; so don't hesitate to ask if something is unclear.
Note that bash [[...]] construct doesn't know about >= operator, so we need to improvise with ! ...<....
This is almost pure bash, no external commands except find. If you accept external commands, $(basename $file) is more obvious than ${file##*/}, but at that point you might as well use awk... and if you can use awk, why not Ruby?
ruby -e "puts Dir['**/*.md'].select{|x| File.basename(x) >= 'aad.md'}"
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I am a new bee to bash scripting. while studying Advanced bash scripting I came across this command. I'm not understand how the command is working and what is the use of curly braces. Thanks in advance.
Your command:
ls . | xargs -i -t cp ./{} $1
could be divided into the following parts:
ls .
List the current directory (this will list all the files/directories but the hidden ones)
| xargs -i -t cp ./{} $1
Basically the xargs breaks the piped output (ls in this case) and provides each element in the list as input to the following command (cp in this case). The -t option is to show in the stderr what xargs is actually executing. The -i is used for string replacement. In this case since nothing has been provided it will substitute the {} by the input. $1 is the name of the destination where your files will be copied (I guess in this case it should be a directory for the command to make sense otherwise you will be copying all the files to the same destination).
So for example, if you have lets say a directory that has files called a, b, c. When you run this command it will perform the following:
cp ./a $1
cp ./b $1
cp ./c $1
NOTE:
The -i option is deprecated, -I (uppercase i) should be used instead
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I have this script I'm studying and I would like to know what is cat doing in this section.
if cat downloaded.txt | grep "$count" >/dev/null
then
echo "File already downloaded!"
else
echo $count >> downloaded.txt
cat $count | egrep -o "http://server.*(png|jpg|gif)" | nice -n -20 wget --no-dns-cache -4 --tries=2 --keep-session-cookies --load-cookies=cookies.txt --referer=http://server.com/wallpaper/$number -i -
rm $count
fi
Like most cats, this is a useless cat.
Instead of:
if cat downloaded.txt | grep "$count" >/dev/null
It could have been written:
if grep "$count" download.txt > /dev/null
In fact, because you've eliminated the pipe, you've eliminated issues with which exit value the if statement is dealing with.
Most Unix cats you'll see are of the useless variety. However, people like cats almost as much as they like using a grep/awk pipe, or using multiple grep or sed commands instead of combining everything into a single command.
The cat command stands for concatenate which is to allow you to concatenate files. It was created to be used with the split command which splits a file into multiple parts. This was useful if you had a really big file, but had to put it on floppy drives that couldn't hold the entire file:
split -b140K -a4 my_really_big_file.txt my_smaller_files.txt.
Now, I'll have my_smaller_files.txt.aaaa and my_smaller_files.txt.aaab and so forth. I can put them on the floppies, and then on the other computer. (Heck, I might go all high tech and use UUCP on you!).
Once I get my files on the other computer, I can do this:
cat my_smaller_files.txt.* > my_really_big_file.txt
And, that's one cat that isn't useless.
cat prints out the contents of the file with the given name (to the standard output or to wherever it's redirected). The result can be piped to some other command (in this case, (e)grep to find something in the file contents). Concretely, here it tries to download the images referenced in that file, then adds the name of the file to downloaded.txt in order to not process it again (this is what the check in if was about).
http://www.linfo.org/cat.html
"cat" is a unix command that reads the contents of one or more files sequentially and by default prints out the information the user console ("stdout" or standard output).
In this case cat is being used to read the contents of the file "downloaded.txt", the pipe "|" is redirecting/feeding its output to the grep program, which is searching for whatever is in the variable "$count" to be matched with.
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When I use ! to execute a previous command it automatically prints the command as well. Is there a way to hide this?
Example:
This is what happens:
ralgrad:~$ echo test
test
ralgrad:~$ !!
echo test
test
This is what I would want:
ralgrad:~$ echo test
test
ralgrad:~$ !!
test
I have looked at the bash source and there is no way to disable this automatic printing of the expanded command. You would have to compile your own version of bash!
If it is particularly important to you for whatever reason, look in bashhist.c in the pre_process_line function and comment out/remove the following line:
printf (stderr, "%s\n", history_value);
You cannot do that with !!, because it repeats the last command not the last output. As far as I know, there is no single command that allows to achieve what you are asking. However, you can try a simple hack:
result=`echo test`
echo "$result"
Well, you can simulate what you want with the following batch file:
if [ -z $1 ]; then
exe=`fc -lrn | awk 'NR==2 {print;}'`
else
exe=`fc -lrn | cut -f2- | awk 'NR>=2 {print;}' | grep "^ $*" | head -n1 `
fi
eval $exe
Let h be the name of the file (or, if you want it, even !). Then you can do:
# echo Foo
Foo
# echo Bar
Bar
# h
Bar
# h echo F
Foo