linux sed II
double space a file
sed G
double space a file which already has blank lines in it. Output file should contain no more than one blank line between lines of text.
sed '/^$/d;G'
triple space a file
sed 'G;G'
undo double-spacing (assumes even-numbered lines are always blank)
sed 'n;d'
insert a blank line above every line which matches "regex"
sed '/regex/{x;p;x;}'
insert a blank line below every line which matches "regex"
sed '/regex/G'
insert a blank line above and below every line which matches "regex"
sed '/regex/{x;p;x;G;}'
number each line of a file (simple left alignment). Using a tab (see note on '\t' at end of file) instead of space will preserve margins.
sed = filename | sed 'N;s/\n/\t/'
number each line of a file (number on left, right-aligned)
sed = filename | sed 'N; s/^/ /; s/ *\(.\{6,\}\)\n/\1 /'
number each line of file, but only print numbers if line is not blank
sed '/./=' filename | sed '/./N; s/\n/ /'
count lines (emulates "wc -l")
sed -n '$='
IN UNIX ENVIRONMENT: convert DOS newlines (CR/LF) to Unix format.
sed 's/.$//' # assumes that all lines end with CR/LF sed 's/^M$//' # in bash/tcsh, press Ctrl-V then Ctrl-M sed 's/\x0D$//' # works on ssed, gsed 3.02.80 or higher
IN UNIX ENVIRONMENT: convert Unix newlines (LF) to DOS format.
sed "s/$/`echo -e \\\r`/" # command line under ksh sed 's/$'"/`echo \\\r`/" # command line under bash sed "s/$/`echo \\\r`/" # command line under zsh sed 's/$/\r/' # gsed 3.02.80 or higher
delete leading whitespace (spaces, tabs) from front of each line
aligns all text flush leftsed 's/^[ \t]*//' # see note on '\t' at end of file
delete trailing whitespace (spaces, tabs) from end of each line
sed 's/[ \t]*$//' # see note on '\t' at end of file
delete BOTH leading and trailing whitespace from each line
sed 's/^[ \t]*//;s/[ \t]*$//'
insert 5 blank spaces at beginning of each line (make page offset)
sed 's/^/ /'
align all text flush right on a 79-column width
sed -e :a -e 's/^.\{1,78\}$/ &/;ta' # set at 78 plus 1 space
center all text in the middle of 79-column width. In method 1, spaces at the beginning of the line are significant, and trailing spaces are appended at the end of the line. In method 2, spaces at the beginning of the line are discarded in centering the line, and no trailing spaces appear at the end of lines.
sed -e :a -e 's/^.\{1,77\}$/ & /;ta' # method 1
sed -e :a -e 's/^.\{1,77\}$/ &/;ta' -e 's/\( *\)\1/\1/' # method 2
substitute (find and replace) "foo" with "bar" on each line
sed 's/foo/bar/' # replaces only 1st instance in a line sed 's/foo/bar/4' # replaces only 4th instance in a line sed 's/foo/bar/g' # replaces ALL instances in a line sed 's/\(.*\)foo\(.*foo\)/\1bar\2/' # replace the next-to-last case sed 's/\(.*\)foo/\1bar/' # replace only the last case
substitute "foo" with "bar" ONLY for lines which contain "baz"
sed '/baz/s/foo/bar/g'
substitute "foo" with "bar" EXCEPT for lines which contain "baz"
sed '/baz/!s/foo/bar/g'
change "scarlet" or "ruby" or "puce" to "red"
sed 's/scarlet/red/g;s/ruby/red/g;s/puce/red/g' # most seds gsed 's/scarlet\|ruby\|puce/red/g' # GNU sed only
reverse order of lines (emulates "tac") bug/feature in HHsed v1.5 causes blank lines to be deleted
sed '1!G;h;$!d' # method 1 sed -n '1!G;h;$p' # method 2
reverse each character on the line (emulates "rev")
sed '/\n/!G;s/\(.\)\(.*\n\)/&\2\1/;//D;s/.//'
join pairs of lines side-by-side (like "paste")
sed '$!N;s/\n/ /'
if a line ends with a backslash, append the next line to it
sed -e :a -e '/\\$/N; s/\\\n//; ta'
if a line begins with an equal sign, append it to the previous line
# and replace the "=" with a single space sed -e :a -e '$!N;s/\n=/ /;ta' -e 'P;D'
add commas to numeric strings, changing "1234567" to "1,234,567"
gsed ':a;s/\B[0-9]\{3\}\>/,&/;ta' # GNU sed
sed -e :a -e 's/\(.*[0-9]\)\([0-9]\{3\}\)/\1,\2/;ta' # other seds
add commas to numbers with decimal points and minus signs (GNU sed)
gsed -r ':a;s/(^|[^0-9.])([0-9]+)([0-9]{3})/\1\2,\3/g;ta'
add a blank line every 5 lines (after lines 5, 10, 15, 20, etc.)
gsed '0~5G' # GNU sed only sed 'n;n;n;n;G;' # other seds
Linux - system, cmds & shell
- Linux Tips - links, vmstats, rsync
- Linux Tips 2 - ctrl a, curl r, tail -f, umask
- Linux - bash I
- Linux - bash II
- Linux - Uncompressing 7z file
- Linux - sed I (substitution: sed 's///', sed -i)
- Linux - sed II (file spacing, numbering, text conversion and substitution)
- Linux - sed III (selective printing of certain lines, selective definition of certain lines)
- Linux - 7 File types : Regular, Directory, Block file, Character device file, Pipe file, Symbolic link file, and Socket file
- Linux shell programming - introduction
- Linux shell programming - variables and functions (readonly, unset, and functions)
- Linux shell programming - special shell variables
- Linux shell programming : arrays - three different ways of declaring arrays & looping with $*/$@
- Linux shell programming : operations on array
- Linux shell programming : variables & commands substitution
- Linux shell programming : metacharacters & quotes
- Linux shell programming : input/output redirection & here document
- Linux shell programming : loop control - for, while, break, and break n
- Linux shell programming : string
- Linux shell programming : for-loop
- Linux shell programming : if/elif/else/fi
- Linux shell programming : Test
- Managing User Account - useradd, usermod, and userdel
- Linux Secure Shell (SSH) I : key generation, private key and public key
- Linux Secure Shell (SSH) II : ssh-agent & scp
- Linux Secure Shell (SSH) III : SSH Tunnel as Proxy - Dynamic Port Forwarding (SOCKS Proxy)
- Linux Secure Shell (SSH) IV : Local port forwarding (outgoing ssh tunnel)
- Linux Secure Shell (SSH) V : Reverse SSH Tunnel (remote port forwarding / incoming ssh tunnel) /)
- Linux Processes and Signals
- Linux Drivers 1
- tcpdump
- Linux Debugging using gdb
- Embedded Systems Programming I - Introduction
- Embedded Systems Programming II - gcc ARM Toolchain and Simple Code on Ubuntu/Fedora
- LXC (Linux Container) Install and Run
- Linux IPTables
- Hadoop - 1. Setting up on Ubuntu for Single-Node Cluster
- Hadoop - 2. Runing on Ubuntu for Single-Node Cluster
- ownCloud 7 install
- Ubuntu 14.04 guest on Mac OSX host using VirtualBox I
- Ubuntu 14.04 guest on Mac OSX host using VirtualBox II
- Windows 8 guest on Mac OSX host using VirtualBox I
- Ubuntu Package Management System (apt-get vs dpkg)
- RPM Packaging
- How to Make a Self-Signed SSL Certificate
- Linux Q & A
- DevOps / Sys Admin questions
Ph.D. / Golden Gate Ave, San Francisco / Seoul National Univ / Carnegie Mellon / UC Berkeley / DevOps / Deep Learning / Visualization
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