I have a script: 'analysis.pl' where the number of lines in a separate file are required as an input argument:
perl ./analysis.pl max=[input number of lines in separate file]
It would be very useful if I could give the output of 'wc -l separate_file' as input to the perl script.
max=`wc -l NRL.txt`
echo $max
perl ./analysis.pl max=$max
The problem is that wc -l gives the number of lines and the file name which returns an error as the argument can only take one input....
perl ./analysis.pl max=150000 separate_file ####error
So how can I get wc -l to only return the number of lines and not the file name?
when passing file as standard input wc doesn't echo filename
wc -l < NRL.txt
There are many ways to solve this specifically, but one way is to pipe the output of wc to awk and pull the number out of the output of wc:
max=`wc -l NRL.txt | awk '{print $1}'`
Related
I am interested in counting the number of lines in the output of ps command which I can do with
echo "$(ps | wc -l)"
However, I now have the output of ps command stored in a variable by doing X="$(ps)". How do I pass X to wc -l command without using a pipe? I tried $(wc -l < "$X") but it didn't work. I read the man page for wc and it takes a file as an argument. So I guess another way to frame the question would be - How do I treat value of a variable as a file to pass as an argument to a command in bash script?
I am fairly new to bash scripting and keywords I tried to search with didn't give clear answer to my questions.
I suggest:
echo "$X" | wc -l
or
wc -l <<< "$X"
I can do the following using a for loop
for f in *.txt; do grep 'RINEX' $f |wc -l; done
Is there any possibility to get an individual file report by running one liner?
Meaning that I want to grep & wc one file at the time in a similar fashion like
grep 'RINEX' *.txt
UPDATE:
grep -c 'RINEX' *.txt
returns the name of each file and its corresponding number of occurrences. Thx #Evert
grep is not the right tool for this task.
grep does line based match, e.g. line grep 'o' <<< "fooo" will return 1 line. however we have 3 os.
This one-liner should do what you want:
awk -F'RINEX' 'FILENAME!=f{if(f)print f,s;f=FILENAME;s=0}
{s+=(NF-1)}
END{print f,s}' /path/*.txt
conducting a word count of a directory.
ls | wc -l
if output is "17", I would like the output to display as "017".
I have played with | printf with little luck.
Any suggestions would be appreciated.
printf is the way to go to format numbers:
printf "There were %03d files\n" "$(ls | wc -l)"
ls | wc -l will tell you how many lines it encountered parsing the output of ls, which may not be the same as the number of (non-dot) filenames in the directory. What if a filename has a newline? One reliable way to get the number of files in a directory is
x=(*)
printf '%03d\n' "${#x[#]}"
But that will only work with a shell that supports arrays. If you want a POSIX compatible approach, use a shell function:
countargs() { printf '%03d\n' $#; }
countargs *
This works because when a glob expands the shell maintains the words in each member of the glob expansion, regardless of the characters in the filename. But when you pipe a filename the command on the other side of the pipe can't tell it's anything other than a normal string, so it can't do any special handling.
You coud use sed.
ls | wc -l | sed 's/^17$/017/'
And this applies to all the two digit numbers.
ls | wc -l | sed '/^[0-9][0-9]$/s/.*/0&/'
I have the following three constructs in a bash script:
NUMOFLINES=$(wc -l $JAVA_TAGS_FILE)
echo $NUMOFLINES" lines"
echo $(wc -l $JAVA_TAGS_FILE)" lines"
echo "$(wc -l $JAVA_TAGS_FILE) lines"
And they both produce identical output when the script is run:
121711 /home/slash/.java_base.tag lines
121711 /home/slash/.java_base.tag lines
121711 /home/slash/.java_base.tag lines
I.e. the name of the file is also echoed (which I don't want to). Why do these scriplets fail and how should I output a clean:
121711 lines
?
An Example Using Your Own Data
You can avoid having your filename embedded in the NUMOFLINES variable by using redirection from JAVA_TAGS_FILE, rather than passing the filename as an argument to wc. For example:
NUMOFLINES=$(wc -l < "$JAVA_TAGS_FILE")
Explanation: Use Pipes or Redirection to Avoid Filenames in Output
The wc utility will not print the name of the file in its output if input is taken from a pipe or redirection operator. Consider these various examples:
# wc shows filename when the file is an argument
$ wc -l /etc/passwd
41 /etc/passwd
# filename is ignored when piped in on standard input
$ cat /etc/passwd | wc -l
41
# unusual redirection, but wc still ignores the filename
$ < /etc/passwd wc -l
41
# typical redirection, taking standard input from a file
$ wc -l < /etc/passwd
41
As you can see, the only time wc will print the filename is when its passed as an argument, rather than as data on standard input. In some cases, you may want the filename to be printed, so it's useful to understand when it will be displayed.
wc can't get the filename if you don't give it one.
wc -l < "$JAVA_TAGS_FILE"
You can also use awk:
awk 'END {print NR,"lines"}' filename
Or
awk 'END {print NR}' filename
(apply on Mac, and probably other Unixes)
Actually there is a problem with the wc approach: it does not count the last line if it does not terminate with the end of line symbol.
Use this instead
nbLines=$(cat -n file.txt | tail -n 1 | cut -f1 | xargs)
or even better (thanks gniourf_gniourf):
nblines=$(grep -c '' file.txt)
Note: The awk approach by chilicuil also works.
It's a very simple:
NUMOFLINES=$(cat $JAVA_TAGS_FILE | wc -l )
or
NUMOFLINES=$(wc -l $JAVA_TAGS_FILE | awk '{print $1}')
I normally use the 'back tick' feature of bash
export NUM_LINES=`wc -l filename`
Note the 'tick' is the 'back tick' e.g. ` not the normal single quote
What Linux commands would you use successively, for a bunch of files, to count the number of lines in a file and output to an output file with part of the corresponding input file as part of the output line. So for example we were looking at file LOG_Yellow and it had 28 lines, the the output file would have a line like this (Yellow and 28 are tab separated):
Yellow 28
wc -l [filenames] | grep -v " total$" | sed s/[prefix]//
The wc -l generates the output in almost the right format; grep -v removes the "total" line that wc generates for you; sed strips the junk you don't want from the filenames.
wc -l * | head --lines=-1 > output.txt
produces output like this:
linecount1 filename1
linecount2 filename2
I think you should be able to work from here to extend to your needs.
edit: since I haven't seen the rules for you name extraction, I still leave the full name. However, unlike other answers I'd prefer to use head rather then grep, which not only should be slightly faster, but also avoids the case of filtering out files named total*.
edit2 (having read the comments): the following does the whole lot:
wc -l * | head --lines=-1 | sed s/LOG_// | awk '{print $2 "\t" $1}' > output.txt
wc -l *| grep -v " total"
send
28 Yellow
You can reverse it if you want (awk, if you don't have space in file names)
wc -l *| egrep -v " total$" | sed s/[prefix]//
| awk '{print $2 " " $1}'
Short of writing the script for you:
'for' for looping through your files.
'echo -n' for printing the current file
'wc -l' for finding out the line count
And dont forget to redirect
('>' or '>>') your results to your
output file