Linux Utilities:
AWK:
Remove duplicate lines using awk.
- awk '!($0 in array) { array[$0]; print }' somefile.txt
Print all lines from /etc/passwd that has the same uid and gid (if column 3 = column 4).
- awk -F ':' '$3==$4' /etc/passwd
GREP:
Print the matched line, along with the 3 lines after it.
- grep -A 3 -i "example" somefile.txt
FIND:
Search all .sql files in the system and archive them.
- find / -name *.sql -type f -print | xargs tar -cvzf sqlfiles.tar.gz
SED:
Remove carriage return from the end of a filename.
- sed 's/.$//' somefile.txt
Add line number for all non-empty-lines in a file.
- sed -n '1!G;h;$p' somefile.txt
Search and replace all the strings/patterns without opening a file.
- sed 's/Old/New/' somefile.txt
Replace only the second occurrence on each line.
- sed 's/Old/New/2' somefile.txt
Replace the second occurance of a string in a particular line.
- sed '2 s/Old/New/' somefile.txt
Replace all occurrences of a string/pattern in a file.
- sed 's/Old/New/g' somefile.txt
Exclude lines 2-4 of a file and print the rest.
- sed -n '2,4p' somefile.txt
Print/display multiple consecutive lines (print lines 2 and 3, and 5 and 6).
- sed -n -e '2,3p' -e '5,6p' somefile.txt
Print/display lines which contain a specific word.
- sed -n /operating/p somefile.txt
Add a line in between each line in a file.
- sed G somefile.txt
Eliminate blank lines or ignore them.
- sed '/^$/d' somefile.txt
- sed '/^#\|^$\| *#/d' somefile.conf
Delete all lines except the range specified?
- sed '3,5!d' somefile.txt
Ignore the case-sensitivity when replacing a word replace all (Old or old).
- sed 's/old/new/i' somefile.txt
Top
To display only the processes that belong to a particular user use -u option. The following will show only the top processes that belongs to oracle user.
- top -u oracle
XARGS:
Copy all .jpg images to another directory:
- ls *.jpg | xargs -n1 -i cp {} /another/directory
Download all the URLs listed in filename.txt file:
- cat filename.txt | xargs wget -c