How do I convert multi public key into a single line?
tr -d ‘\n’ < key.txt Found on http://linux.dsplabs.com.au/rmnl-remove-new-line-characters-tr-awk-perl-sed-c-cpp-bash-python-xargs-ghc-ghci-haskell-sam-ssam-p65/
sed
How do I insert a newline/linebreak after a line using sed
For adding a newline after a pattern, you can also say: sed ‘/pattern/{G;}’ filename Quoting GNU sed manual: G Append a newline to the contents of the pattern space, and then append the contents of the hold space to that of the pattern space. EDIT: Incidentally, this happens to be covered in sed one liners: … Read more
Find and Replace string in all files recursive using grep and sed [duplicate]
As @Didier said, you can change your delimiter to something other than /: grep -rl $oldstring /path/to/folder | xargs sed -i s@$oldstring@$newstring@g
sed join lines together
sed ‘:a;/0$/{N;s/\n//;ba}’ In a loop (branch ba to label :a), if the current line ends in 0 (/0$/) append next line (N) and remove inner newline (s/\n//). awk: awk ‘{while(/0$/) { getline a; $0=$0 a; sub(/\n/,_) }; print}’ Perl: perl -pe ‘$_.=<>,s/\n// while /0$/’ bash: while read line; do if [ ${line: -1:1} != “0” … Read more
Text substitution (reading from file and saving to the same file) on linux with sed
On Linux, sed -i is the way to go. sed isn’t actually designed for in-place editing, though; historically, it’s a filter, a program which edits a stream of data in a pipeline, and for this usage you would need to write to a temporary file and then rename it. The reason you get an empty … Read more
‘grep +A’: print everything after a match [duplicate]
AWK If you don’t mind using AWK: awk ‘/yahoo/{y=1;next}y’ data.txt This script has two parts: /yahoo/ { y = 1; next } y The first part states that if we encounter a line with yahoo, we set the variable y=1, and then skip that line (the next command will jump to the next line, thus … Read more
How to add a # before any line containing a matching pattern in BASH?
The following sed command will work for you, which does not require any capture groups: sed /000/s/^/#/ Explanation: /000/ matches a line with 000 s perform a substitution on the lines matched above The substitution will insert a pound character (#) at the beginning of the line (^)
replace a unknown string between two known strings with sed
sed -i ‘s/WORD1.*WORD3/WORD1 foo WORD3/g’ file.txt or sed -i ‘s/(WORD1).*(WORD3)/\1 foo \2/g’ file.txt You might need to escape round brackets, depends on your sed variant.
What does \1 in sed do?
Here’s a simple example: $ echo ‘abcabcabc’ | sed ‘s/\(ab\)c/\1/’ ababcabc $ echo ‘abcabcabc’ | sed ‘s/\(ab\)c/\1/g’ ababab $ echo ‘abcabcabc’ | sed ‘s/\(ab\)\(c\)/\1d\2/g’ abdcabdcabdc In the first command, only the first match is affected. In the second command, every match is affected. In both cases, the \1 refers to the characters captured by the … Read more
Concatenating every other line with the next
This is easiest using paste: paste -s -d’ \n’ input.txt Although there’s a Famous Sed One-Liner (38) to emulate this as in potong’s answer.