The sed (Stream Editor) is very powerful tool. Each line of input is copied into a pattern space. You can run editing commands on each input line to delete or change the input. For example, delete lines containing word DVD, enter:
cat input.txt | sed ‘/DVD/d’
To Print the lines between each pair of words pen and pencil, inclusive, enter:
$ cat input.txt sed -e '/^PEN/,/^PENCIL/p'
To remove all blank lines, enter:
$ cat /etc/rssh.conf | sed '/^$/d' > /tmp/output.file
sed is very handy tool for editing and deleting unwanted stuff. Following echo statements printed lots of whitespace from left side:
echo " This is a test"
Output:
This is a test
To remove all whitespace (including tabs) from left to first word, enter:
echo " This is a test" | sed -e 's/^[ \t]*//'
Output:
This is a test
Where,
- s/ : Substitute command ~ replacement for pattern (^[ \t]*) on each addressed line
- ^[ \t]* : Search pattern ( ^ – start of the line; [ \t]* match one or more blank spaces including tab)
- // : Replace (delete) all matched pattern
Following sample script reads some data from text file and generate a formatted output. It delete all leading whitespace from front of each line so that text get aligned to left:
#!/bin/bash FILE=url.dump.txt DOMAIN=yourdomain.com exec 3<&0 exec 0<$FILE while read line do url=$(echo "http://${DOMAIN}${line}") title="$(lynx -dump -source ${url} | grep '<title>' | awk -F '<title>' '{ print $2 }' | cut -d'<' -f1|sed 's/^[ \t]*//')" echo "<li>${title}</li>" done exec 0<&3 |
To delete trailing whitespace from end of each line, enter:
$ cat input.txt | sed 's/[ \t]*$//' > output.txt
Better remove all leading and trailing whitespace from end of each line:
$ cat input.txt | sed 's/^[ \t]*//;s/[ \t]*$//' > output.txt
14 comment
http://sed.sourceforge.net/sed1line.txt is a very handy document for sed too.
Thanks for sharing the link
Another great resource:
A list of Commands very well written
http://student.northpark.edu/pemente/sed/sed1line.txt
Please stop masturbating and use expand/unexpand.
Some nice examples, but there’s unnecessary use of a cat process for the examples with input.txt. For example,
cat input.txt | sed ‘/DVD/d’ is more efficient as sed ‘/DVD/d’ input.txt
$ cat input.txt sed -e ‘/^PEN/,/^PENCIL/p’ is more efficent as sed -e ‘/^PEN/,/^PENCIL/p’ input.txt
perl -pi -e ‘s,[rn],,g’ file.xml
Thanks for sharing …
better example yet….
cat /usr/bin/scrub
# Remove all comments and empty lines
sed -e ‘s/#.*//’ -e ‘s/[ ^I]*$//’ -e ‘/^$/ d’ $1
cat /usr/bin/clrspace
# Remove all leading and trailing whitespace from each line;
sed ‘s/^[ t]*//;s/[ t]*$//’ $1
now you can simply run
scrub filename
clrspace filename
I tried your sed syntax for leading/trailing space/tabs removal and it doesn’t do it as expected:
# sed s/$/G/g test_file
/etcG
/homeG
/usr/sbin/snapshotsG
/usr/local/etcG
/var/spool/cron/crontabsG
G
/ G
/ /dgdkjgd G
/G
/ /fff/f/ff G
G
/sdfsfssf G
#/sfsfsfG
/sfsd/sfd / G
/sfsd/sfdsfs /dfgf/df/G
/dfgdg /gddd /G
# sed ‘s/^[ t]*//;s/[ t]*$//’ test_file|sed s/$/G/g
/etcG
/homeG
/usr/sbin/snapshotsG
/usr/local/etcG
/var/spool/cron/crontabsG
G
/G
/ /dgdkjgd G
/G
/ /fff/f/ff G
G
/sdfsfssfG
#/sfsfsfG
/sfsd/sfd / G
/sfsd/sfdsfs /dfgf/df/G
/dfgdg /gddd /G
#
ok, I found another solution for it:
sed ‘s/^[[:space:]]*//;s/[[:space:]]*$//’
did the trick.
Hi,
how can I remove spaces at the end of each line in a *.txt file…e.g.
word1[space]
word2[space]
word3[space]
.
.
word n[space]
commands you stated didnt work
sed -i ‘s/W*$//gi’ FILENAME
sed ‘s/[ t]*$//g’
ls *XONE* | wc -w | sed ‘s/ *//’