So in Linux, less is used to read files page by page for better readability. I was wondering if you can do something like less file.txt > output.txt to get one page worth of file.txt and output/write it to `output.txt.
Apparently, this does not work, output.txt is exactly the same as the original file, I'm wondering why this is the case, and if there are other work-arounds. Thank you!
You can use the split command.
split -l 100 -d -a 3 input output
This will split the input file every 100 lines (-l 100), will use numbers as suffixes (-d) and will use 3 numbers as suffix (-a 3) in the output file. Something like this output000, output001, output002
You can use head to get a specific number of lines, and tput lines to see how many lines there are on your current terminal.
Here's a script that fetches a pageful, or the standard 25 lines if no terminal is available:
#!/bin/bash
lines=$(tput lines) || lines=25
head -n "$lines" file.txt > output.txt
we use head and tail to get n lines of top or bottom part of a file
cat /var/log/messages|tail -n20
head -n10 src/main.h
I use
tail -f file | grep pattern
all the time for continuous grep.
However, is there a way I can make grep output its pattern at the same spot, say at the top of the screen? so that the screen doesn't scroll all the time?
My case is something like this: tail -f log_file | grep Status -A 2 will show the current status and what changed it to that status. The problem is the screen scrolls and it becomes annoying. I'd rather have the output stuck on the first 3 lines in the screen.
Thank you!
you could use the watch command; which will always execute the same command, but the position on the screen will stay the same. The process might eat some more CPU or memory though:
watch "tail file | grep pattern"
by default watch executes that command every 2 seconds. You can adjust up to 0.1 seconds using:
watch -n 0.1
NOTE
As noted by #etanReisner: this is not exactly the same as tail -f: tail -f will change immediately if something is added to your logfile, the watch command will only notice that when it executes, ie every 2 (or 0.1 seconds).
Assuming you are using a vt100 compatible emulator...
This command will tail a file, pipe it into grep, read it a line at a time and then display it in reverse on the top line of the screen:
TOSL=$(tput sc;tput cup 0 0;tput rev;tput el)
FROMSL=$(tput sgr0; tput rc)
tail -f file | grep --line-buffered pattern | while read line
do
echo -n "$TOSL${line}$FROMSL"
done
It assumes your output appears a line at a time. If you want more than one line, you can read more than a line, but you have to decide how you want to buffer the output. You could also use the csr terminfo command to set up an entire separate scrolling region instead of just having one line.
Here is the scrolling region version with a ten line status area at the top:
TOSL=$(tput sc; tput csr 0 10; tput cup 10 0;tput rev;tput el)
FROMSL=$(tput sgr0; tput rc;tput csr 10 50;tput rc)
tail -f file | grep --line-buffered pattern | while read line
do
echo -n "$TOSL${line}
$FROMSL"
done
Note that it is not impossible that your display will be corrupted from time-to-time as it could be that the output from your main shell and your background task get mixed up.
Simply replace the newlines with carriage returns.
tail -f file | grep --line-buffered whatever | tr '\012' '\015'
The line buffering is to avoid jumpy output; see http://mywiki.wooledge.org/BashFAQ/009
This is quick and dirty. As noted in comments, this will leave the previous contents of the line underneath, so a shorter line will not completely overlay a longer line. You could add some control codes to address that, but then you might as well use Curses for the formatting too, like in rghome's answer.
Is there a way to modify so that the tail -f lists the line number of the current file as well.
Something similar to grep -n <Strings> *.
Try less
Instead of using tail to follow data and less or nl for numbering, I suggest using a single tool for both:
less -N +F <filename>
This will make less print line numbers and follow the file. From man less:
F
Scroll forward, and keep trying to read when the end of file is reached. Normally this command would be used when already at the end of the file. It is a way to monitor the tail of a file which is growing while it is being viewed. (The behavior is similar to the tail -f command.)
You could do a Ctrl+C to stop following when inside less; to start following again, you could press F again. With this method, you get the additional goodies that less offers like regex-based search, tags, etc.
This command takes into account the number of lines above also
tail -f -n +1 yourfile.txt | nl
You can use less command,
tail -f <filename> | less -N
According to man page of less
-N or --LINE-NUMBERS
Causes a line number to be displayed at the beginning of each
line in the display.
I see that when I use rsync with the -v option it prints the changed files list and some useful infos at the end, like the total transfer size.
Is it somewhat possible to cut out the first (long) part and just print the stats? I am using it in a script, and the log shouldn't be so long. Only the stats are useful.
Thank you.
As I was looking for an answer and came across this question:
rsync also supports the --stats option.
Best solution for now i think :
rsync --info=progress0,name0,flist0,stats2 ...
progress0 hides progress
progress2 display progress
name0 hides file names
stats2 displays stats at the end of transfer
This solution is more a "hack" than the right way to do it because the output is generated but only filtered afterwards. You can use the option --out-format.
rsync ... --out-format="" ... | grep -v -E "^sending|^created" | tr -s "\n"
The grep filter should probably be updated with unwanted lines you see in the output. The tr is here to filter the long sequence of carriage returns.
grep -E for extended regexes
grep -v to invert the match. "Selected lines are those not matching any of the specified patterns."
tr -s to squeeze the repeated carriage returns into a single one
I have the following data, and I need to put it all into one line.
I have this:
22791
;
14336
;
22821
;
34653
;
21491
;
25522
;
33238
;
I need this:
22791;14336;22821;34653;21491;25522;33238;
EDIT
None of these commands is working perfectly.
Most of them let the data look like this:
22791
;14336
;22821
;34653
;21491
;25522
tr --delete '\n' < yourfile.txt
tr -d '\n' < yourfile.txt
Edit:
If none of the commands posted here are working, then you have something other than a newline separating your fields. Possibly you have DOS/Windows line endings in the file (although I would expect the Perl solutions to work even in that case)?
Try:
tr -d "\n\r" < yourfile.txt
If that doesn't work then you're going to have to inspect your file more closely (e.g. in a hex editor) to find out what characters are actually in there that you want to remove.
tr -d '\n' < file.txt
Or
awk '{ printf "%s", $0 }' file.txt
Or
sed ':a;N;$!ba;s/\n//g' file.txt
This page here has a bunch of other methods to remove newlines.
edited to remove feline abuse :)
perl -p -i -e 's/\R//g;' filename
Must do the job.
paste -sd "" file.txt
Expanding on a previous answer, this removes all new lines and saves the result to a new file (thanks to #tripleee):
tr -d '\n' < yourfile.txt > yourfile2.txt
Which is better than a "useless cat" (see comments):
cat file.txt | tr -d '\n' > file2.txt
Also useful for getting rid of new lines at the end of the file, e.g. created by using echo blah > file.txt.
Note that the destination filename is different, important, otherwise you'll wipe out the original content!
You can edit the file in vim:
$ vim inputfile
:%s/\n//g
use
head -n 1 filename | od -c
to figure WHAT is the offending character.
then use
tr -d '\n' <filename
for LF
tr -d '\r\n' <filename
for CRLF
Use sed with POSIX classes
This will remove all lines containing only whitespace (spaces & tabs)
sed '/^[[:space:]]*$/d'
Just take whatever you are working with and pipe it to that
Example
cat filename | sed '/^[[:space:]]*$/d'
Using man 1 ed:
# cf. http://wiki.bash-hackers.org/doku.php?id=howto:edit-ed
ed -s file <<< $'1,$j\n,p' # print to stdout
ed -s file <<< $'1,$j\nwq' # in-place edit
xargs consumes newlines as well (but adds a final trailing newline):
xargs < file.txt | tr -d ' '
Nerd fact: use ASCII instead.
tr -d '\012' < filename.extension
(Edited cause i didn't see the friggin' answer that had same solution, only difference was that mine had ASCII)
Using the gedit text editor (3.18.3)
Click Search
Click Find and Replace...
Enter \n\s into Find field
Leave Replace with blank (nothing)
Check Regular expression box
Click the Find button
Note: this doesn't exactly address the OP's original, 7 year old problem but should help some noob linux users (like me) who find their way here from the SE's with similar "how do I get my text all on one line" questions.
Was having the same case today, super easy in vim or nvim, you can use gJ to join lines. For your use case, just do
99gJ
this will join all your 99 lines. You can adjust the number 99 as need according to how many lines to join. If just join 1 line, then only gJ is good enough.
$ perl -0777 -pe 's/\n+//g' input >output
$ perl -0777 -pe 'tr/\n//d' input >output
If the data is in file.txt, then:
echo $(<file.txt) | tr -d ' '
The '$(<file.txt)' reads the file and gives the contents as a series of words which 'echo' then echoes with a space between them. The 'tr' command then deletes any spaces:
22791;14336;22821;34653;21491;25522;33238;
Assuming you only want to keep the digits and the semicolons, the following should do the trick assuming there are no major encoding issues, though it will also remove the very last "newline":
$ tr -cd ";0-9"
You can easily modify the above to include other characters, e.g. if you want to retain decimal points, commas, etc.
I usually get this usecase when I'm copying a code snippet from a file and I want to paste it into a console without adding unnecessary new lines, I ended up doing a bash alias
( i called it oneline if you are curious )
xsel -b -o | tr -d '\n' | tr -s ' ' | xsel -b -i
xsel -b -o reads my clipboard
tr -d '\n' removes new lines
tr -s ' ' removes recurring spaces
xsel -b -i pushes this back to my clipboard
after that I would paste the new contents of the clipboard into oneline in a console or whatever.
I would do it with awk, e.g.
awk '/[0-9]+/ { a = a $0 ";" } END { print a }' file.txt
(a disadvantage is that a is "accumulated" in memory).
EDIT
Forgot about printf! So also
awk '/[0-9]+/ { printf "%s;", $0 }' file.txt
or likely better, what it was already given in the other ans using awk.
You are missing the most obvious and fast answer especially when you need to do this in GUI in order to fix some weird word-wrap.
Open gedit
Then Ctrl + H, then put in the Find textbox \n and in Replace with an empty space then fill checkbox Regular expression and voila.
To also remove the trailing newline at the end of the file
python -c "s=open('filename','r').read();open('filename', 'w').write(s.replace('\n',''))"
fastest way I found:
open vim by doing this in your commandline
vim inputfile
press ":" and input the following command to remove all newlines
:%s/\n//g
Input this to also remove spaces incase some characters were spaces :%s/ //g
make sure to save by writing to the file with
:w
The same format can be used to remove any other characters, you can use a website like this
https://apps.timwhitlock.info/unicode/inspect
to figure out what character you're missing
You can also use this to figure out other characters you can't see and they have a tool as well
Tool to learn of other invisible characters