> For the complete documentation index, see [llms.txt](https://alomancy.gitbook.io/guides/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://alomancy.gitbook.io/guides/cheat-sheets/bash-cheat-sheets/sed.md). # Sed ## Sed ### **Remove the 1st line** ``` sed 1d filename ``` ### **Remove the first 100 lines (remove line 1-100)** ``` sed 1,100d filename ``` ### **Remove lines with string (e.g. 'bbo')** ``` sed "/bbo/d" filename # case insensitive: sed "/bbo/Id" filename ``` ### **Remove lines whose nth character not equal to a value (e.g. 5th character not equal to 2)** ``` sed -E '/^.{5}[^2]/d' #aaaa2aaa (you can stay) #aaaa1aaa (delete!) ``` ### **Edit infile (edit and save to file), (e.g. deleting the lines with 'bbo' and save to file)** ``` sed -i "/bbo/d" filename ``` ### **When using variable (e.g. $i), use double quotes " "** ``` # e.g. add >$i to the first line (to make a bioinformatics FASTA file) sed "1i >$i" # notice the double quotes! in other examples, you can use a single quote, but here, no way! # '1i' means insert to first line ``` ### **Using environment variable and end-of-line pattern at the same time.** ``` # Use backslash for end-of-line $ pattern, and double quotes for expressing the variable sed -e "\$s/\$/\n+--$3-----+/" ``` ### **Delete/remove empty lines** ``` sed '/^\s*$/d' # or sed '/^$/d' ``` ### **Delete/remove last line** ``` sed '$d' ``` ### **Delete/remove last character from end of file** ``` sed -i '$ s/.$//' filename ``` ### **Add string to beginning of file (e.g. "\[")** ``` sed -i '1s/^/[/' file ``` ### **Add string at certain line number (e.g. add 'something' to line 1 and line 3)** ``` sed -e '1isomething -e '3isomething' ``` ### **Add string to end of file (e.g. "]")** ``` sed '$s/$/]/' filename ``` ### **Add newline to the end** ``` sed '$a\' ``` ### **Add string to beginning of every line (e.g. 'bbo')** ``` sed -e 's/^/bbo/' file ``` ### **Add string to end of each line (e.g. "}")** ``` sed -e 's/$/\}\]/' filename ``` ### **Add \n every nth character (e.g. every 4th character)** ``` sed 's/.\{4\}/&\n/g' ``` ### **Concatenate/combine/join files with a seperator and next line (e.g separate by ",")** ``` sed -s '$a,' *.json > all.json ``` ### **Substitution (e.g. replace A by B)** ``` sed 's/A/B/g' filename ``` ### **Substitution with wildcard (e.g. replace a line start with aaa= by aaa=/my/new/path)** ``` sed "s/aaa=.*/aaa=\/my\/new\/path/g" ``` ### **Select lines start with string (e.g. 'bbo')** ``` sed -n '/^@S/p' ``` ### **Delete lines with string (e.g. 'bbo')** ``` sed '/bbo/d' filename ``` ### **Print/get/trim a range of line (e.g. line 500-5000)** ``` sed -n 500,5000p filename ``` ### **Print every nth lines** ``` sed -n '0~3p' filename # catch 0: start; 3: step ``` ### **Print every odd # lines** ``` sed -n '1~2p' ``` ### **Print every third line including the first line** ``` sed -n '1p;0~3p' ``` ### **Remove leading whitespace and tabs** ``` sed -e 's/^[ \t]*//' # Notice a whitespace before '\t'!! ``` ### **Remove only leading whitespace** ``` sed 's/ *//' # notice a whitespace before '*'!! ``` ### **Remove ending commas** ``` sed 's/,$//g' ``` ### **Add a column to the end** ``` sed "s/$/\t$i/" # $i is the valuable you want to add # To add the filename to every last column of the file for i in $(ls);do sed -i "s/$/\t$i/" $i;done ``` ### **Add extension of filename to last column** ``` for i in T000086_1.02.n T000086_1.02.p;do sed "s/$/\t${i/*./}/" $i;done >T000086_1.02.np ``` ### **Remove newline\ nextline** ``` sed ':a;N;$!ba;s/\n//g' ``` ### **Print a particular line (e.g. 123th line)** ``` sed -n -e '123p' ``` ### **Print a number of lines (e.g. line 10th to line 33 rd)** ``` sed -n '10,33p' AAA#AAA)** ``` sed -r -e 's/^.{3}/&#/' file ```