I am trying to print all files in /usr/bin/ where the filename starts with a v. This works,
ls -lA /usr/bin/ | awk '{print $9}' | grep ^v
Surprisingly, this returns no output,
ls -lA /usr/bin/ | awk '/^v/ {print $9}'.
I don't understand the difference. I am running Ubuntu 21.10 with awk -W version saying that it is on 1.3.4 20200120.
Edit: I understand that awk may not be the best way to accomplish what I am wanting to do here. But, this is an exercise in learning awk by testing my understanding via comparing it to the real output.
The difference between the two pipelines is that the first outputs the 9th column and then check to see if that starts with a v the second checks to see if the line starts with a v, change the second to:
$ ls -lA /usr/bin/ | awk '$9 ~ /^v/ {print $9}'
When writing:
/pattern/ { ... }
it's the same as writing
$0 ~ /pattern/ { ... }
but in your case you want to compare the 9th column, so write that instead.
But you really don't want to create a pipeline for this, and what would happen if your files contain a space?
You can consider using find or globs instead:
$ printf '%s\n' /usr/bin/v*
/usr/bin/vi
/usr/bin/view
...
or
$ find /usr/bin -name 'v*' -print
/usr/bin/vi
/usr/bin/view
...
I have csv files that need to be changed f -> 0 and t -> 1 only between commas for every single csv if it matches. From:
,t,t,f,f,a,t,f,t,f,f,t,f,
tftf
to:
,1,1,0,0,a,1,0,1,0,0,1,0,
tftf
Works this way, but want to know better way that could reduce the replacing time consume
for i in 1 2 3 4 5 6
do
echo "converting tables for mariaDB"
find ./ -type f -name "*.csv" -print0 | xargs -0 sed -i 's/\,t\,/\,1\,/g'
find ./ -type f -name "*.csv" -print0 | xargs -0 sed -i 's/\,f\,/\,0\,/g'
echo "$i time(s) changed "
done
I except , one single command will change the line
Could you please try following. Though it is not perfect solution but would be simplest use it in case you don't have gawk's latest version where -inplace edit option is present.
for file in *.csv
awk '{gsub(/,t,/,",1,");gsub(/,f,/,",0,");gsub(/,t,/,",1,");gsub(/,f,/,",0,")} 1' "$file" > temp && mv temp"$file"
done
OR
for file in *.csv
awk -v t_val="1" -v f_val="0" 'BEGIN{FS=OFS=","}{for(i=2;i<NF;i++){$i=($i=="t"?t_val:$i=="f"?f_val:$i)}} 1' "$file" > temp && mv temp "$file"
done
2nd solution: Using gawk's latest version where we could save edit into Input_file itself.
gawk -i inplace '{gsub(/,t,/,",1,");gsub(/,f,/,",0,");gsub(/,t,/,",1,");gsub(/,f,/,",0,")} 1' *.csv
OR
gawk -i inplace -v t_val="1" -v f_val="0" 'BEGIN{FS=OFS=","}{for(i=2;i<NF;i++){$i=($i=="t"?t_val:$i=="f"?f_val:$i)}} 1' Input_file
The main problem, in this case, is that a regular expression does not allow overlap when parsing it with sed 's/ere/str/g' or awk '{gsub(ere,str,$0)}'. This comment nicely explains how you can circumvent this in sed using the t<label> command, which means: if a change happened to the pattern space, move to <label>. The comment shows a generic way of doing it. The awk alternative to this rule would be:
$ awk '{while(match($0,ere)) gsub(ere,str)}'
An alternative sed solution in the case of the OP's example could use the following idea:
duplicate all commas. Since we are searching for strings of the form ",t,", this duplication avoid overlap using s.
since no overlap is possible, replace all ",f," with ",0," and all ",t," with ",1,".
We can now revert all duplicated commas again. As no overlap is allowed, sequences like ,,,, will be nicely converted to ,, and not ,
In POSIX sed this looks like:
$ sed -e 's/,/,,/g' -e 's/,f,/,0,/g' \
-e 's/,t,/,1,/g' -e 's/,,/,/g' file > file.tmp
$ mv file.tmp file
With GNU sed we can do it in one go:
$ sed -i 's/,/,,/g;s/,f,/,0,/g;s/,t,/,1,/g;s/,,/,/g' file
With awk, this would look like:
$ awk 'BEGIN{FS=",";OFS=FS FS}
{$1=$1;gsub(/,f,/,",0,");gsub(/,t,/,",1,");gsub(OFS,FS)}1' file > file.tmp
$ mv file.tmp file
I have some files which have wrong time and date, but the filename contains the correct time and date and I try to write a script to fix this with the touch command.
Example of filename:
071212_090537.jpg
I would like this to be converted to the following format:
1712120905.37
Note, the year is listed as 07 in the filename, even if it is 17 so I would like the first 0 to be changed to 1.
How can I do this using awk or sed?
I'm quite new to awk and sed, an programming in general. Have tried to search for a solution and instruction, but haven't manage to figure out how to solve this.
Can anyone help me?
Thanks. :)
Take your example:
awk -F'[_.]' '{$0=$1$2;sub(/^./,"1");sub(/..$/,".&")}1'<<<"071212_090537.jpg"
will output:
1712120905.37
If you want the file to be removed, you can let awk generate the mv origin new command, and pipe the output to |sh, like: (comments inline)
listYourFiles| # list your files as input to awk
awk -F'[_.]' '{o=$0;$0=$1$2;sub(/^./,"1");sub(/..$/,".&");
printf "mv %s %s\n",o,$0 }1' #this will print "mv ori new"
|sh # this will execute the mv command
It's completely unnecessary to call awk or sed for this, you can do it in your shell. e.g. with bash:
$ f='071212_090537.jpg'
$ [[ $f =~ ^.(.*)_(.*)(..)\.[^.]+$ ]]
$ echo "1${BASH_REMATCH[1]}${BASH_REMATCH[2]}.${BASH_REMATCH[3]}"
1712120905.37
This is probably what you're trying to do:
for old in *.jpg; do
[[ $old =~ ^.(.*)_(.*)(..)\.[^.]+$ ]] || { printf 'Warning, unexpected old file name format "%s"\n' "$old" >&2; continue; }
new="1${BASH_REMATCH[1]}${BASH_REMATCH[2]}.${BASH_REMATCH[3]}"
[[ -f "$new" ]] && { printf 'Warning, new file name "%s" generated from "%s" already exists, skipping.\n' "$new" "$old" >&2; continue; }
mv -- "$old" "$new"
done
You need that test for new already existing since an old of 071212_090537.jpg or 171212_090537.jpg (or various other values) would create the same new of 1712120905.37
I think sed really is the easiest solution:
You could do this:
▶ for f in *.jpg ; do
new_f=$(sed -E 's/([0-9]{6})_([0-9]{4})([0-9]{2})\.jpg/\1\2.\3.jpg/' <<< $f)
mv $f $new_f
done
For more info:
You probably need to read an introductory tutorial on regular expressions.
Note that the -E option to sed allows use of extended regular expressions, allowing a more readable and convenient expression here.
Use of <<< is a Bashism known as a "here-string". If you are using a shell that doesn't support that, A <<< $b can be rewritten as echo $b | A.
Testing:
▶ touch 071212_090538.jpg 071212_090539.jpg
▶ ls -1 *.jpg
071212_090538.jpg
071212_090539.jpg
▶ for f in *.jpg ; do
new_f=$(sed -E 's/([0-9]{6})_([0-9]{4})([0-9]{2})\.jpg/\1\2.\3.jpg/' <<< $f)
mv $f $new_f
done
▶ ls -1
0712120905.38.jpg
0712120905.39.jpg
i have hundreads of folders with a subfolder named "thumbs" under each folder. i need to change the "thumbs" subfolder name with "thumb", under each subfolder.
i tried
find . -type d -exec rename 's/^thumbs$/thumb/' {} ";"
and i run this in shell when i am inside the folder that contains all subfolders, and each one of these subfolders contains the "thumbs" folder that need to be renamed with "thumb".
well I ran that command and shell stayed a lot of time thinking, then i gave a CTRL+C to stop, but I checked and no folder was renamed under current directory, I dont know if i renamed folders outside the directory i was in, can someone tell me where i am wrong with the code?
Goal 1: To change a subfolder "thumbs" to "thumb" if only one level deep.
Example Input:
./foo1/thumbs
./foo2/thumbs
./foo2/thumbs
Solution:
find . -maxdepth 2 -type d | sed 'p;s/thumbs/thumb/' | xargs -n2 mv
Output:
./foo1/thumb
./foo2/thumb
./foo2/thumb
Explanation:
Use find to give you all "thumbs" folders only one level deep. Pipe the output to sed. The p option prints the input line and the rest of the sed command changes "thumbs" to "thumb". Finally, pipe to xargs. The -n2 option tells xargs to use two arguments from the pipe and pass them to the mv command.
Issue:
This will not catch deeper subfolders. You can't simple not use depth here because find prints the output from the top and since we are replacing things with sed before we mv, mv will result in a error for deeper subfolders. For example, ./foo/thumbs/thumbs/ will not work because mv will take care of ./foo/thumbs first and make it ./foo/thumb, but then the next output line will result in an error because ./foo/thumbs/thumbs/ no longer exist.
Goal 2: To change all subfolders "thumbs" to "thumb" regardless of how deep.
Example Input:
./foo1/thumbs
./foo2/thumbs
./foo2/thumbs/thumbs
./foo2/thumbs
Solution:
find . -type d | awk -F'/' '{print NF, $0}' | sort -k 1 -n -r | awk '{print $2}' | sed 'p;s/\(.*\)thumbs/\1thumb/' | xargs -n2 mv
Output:
./foo1/thumb
./foo2/thumb
./foo2/thumb/thumb
./foo2/thumb
Explanation:
Use find to give you all "thumbs" subfolders. Pipe the output to awk to print the number of '/'s in each path plus the original output. sort the output numerically, in reverse (to put the deepest paths on top) by the number of '/'s. Pipe the sorted list to awk to remove the counts from each line. Pipe the output to sed. The p option prints the input line and the rest of the sed command finds the last occurrence of "thumbs" and changes only it to "thumb". Since we are working with sorted list in the order of deepest to shallowest level, this will provide mv with the right commands. Finally, pipe to xargs. The -n2 option tells xargs to use two arguments from the pipe and pass them to the mv command.
I have a lot of text files in which I would like to find the word 'CASE' and replace it with the related filename.
I tried
find . -type f | while read file
do
awk '{gsub(/CASE/,print "FILENAME",$0)}' $file >$file.$$
mv $file.$$ >$file
done
but I got the following error
awk: syntax error at source line 1 context is >>> {gsub(/CASE/,print <<< "CASE",$0)}
awk: illegal statement at source line 1
I also tried
for i in $(ls *);
do
awk '{gsub(/CASE/,${i},$0)}' ${i} > file.txt;
done
getting an empty output and
awk: syntax error at source line 1 context is >>> {gsub(/CASE/,${ <<<
awk: illegal statement at source line 1
Why awk? sed is what you want:
while read -r file; do
sed -i "s/CASE/${file##*/}/g" "$file"
done < <( find . -type f )
or
while read -r file; do
sed -i.bak "s/CASE/${file##*/}/g" "$file"
done < <( find . -type f )
To create a backup of the original.
You didn't post any sample input and expected output so this is a guess but maybe this is what you want:
find . -type f |
while IFS= read -r file
do
awk '{gsub(/CASE/,FILENAME)} 1' "$file" > "${file}.$$" &&
mv "${file}.$$" "$file"
done
Every change I made to the shell code is important so if you don't understand why I changed any part of it, ask the question.
btw if after making the changes you are still getting the error message:
awk: syntax error at source line 1
awk: illegal statement at source line 1
then you are using old, broken awk (/usr/bin/awk on Solaris). Never use that awk. On Solaris use /usr/xpg4/bin/awk (or nawk if you must).
Caveats: the above will fail if your file name contains newlines or ampersands (&) or escaped digits (e.g. \1). See Is it possible to escape regex metacharacters reliably with sed for details. If any of that is a problem, post some representative sample input and expected output.
print in that first script is the error.
The second argument to gsub is the replacement string not a command.
You want just FILENAME. (Note not "FILENAME" that's a literal string. FILENAME the variable.)
find . -type f -print0 | while IFS= read -d '' file
do
awk '{gsub(/CASE/,FILENAME,$0)} 7' "$file" >"$file.$$"
mv "$file.$$" "$file"
done
Note that I quoted all your variables and fixed your find | read pipeline to work correctly for files with odd characters in the names (see Bash FAQ 001 for more about that). I also fixed the erroneous > in the mv command.
See the answers on this question for how to properly escape the original filename to make it safe to use in the replacement portion of gsub.
Also note that recent (4.1+ I believe) versions of awk have the -i inplace argument.
To fix the second script you need to add the quotes you removed from the first script.
for i in *; do awk '{gsub(/CASE/,"'"${i}"'",$0)}' "${i}" > file.txt; done
Note that I got rid of the worse than useless use of ls (worse than useless because it actively breaks files with spaces or shell metacharacters in the their names (see Parsing ls for more on that).
That command though is somewhat ugly and unsafe for filenames with various characters in them and would be better written as the following though:
for i in *; do awk -v fname="$i" '{gsub(/CASE/,fname,$0)}' "${i}" > file.txt; done
since that will work with filenames with double quotes/etc. in their names correctly whereas the direct variable expansion version will not.
That being said the corrected first script is the right answer.