How to remove ^[, and all of the escape sequences in a file using linux shell scripting

We want to remove ^[, and all of the escape sequences.

sed is not working and is giving us this error:

$ sed 's/^[//g' oldfile > newfile; mv newfile oldfile;
sed: -e expression #1, char 7: unterminated `s' command

$ sed -i '' -e 's/^[//g' somefile
sed: -e expression #1, char 7: unterminated `s' command

Are you looking for ansifilter?

---

Two things you can do: enter the literal escape (in bash:)

Using keyboard entry:

sed 's/Ctrl-vEsc//g'

alternatively

sed 's/Ctrl-vCtrl-[//g'

Or you can use character escapes:

sed 's/\x1b//g'

or for all control characters:

sed 's/[\x01-\x1F\x7F]//g' # NOTE: zaps TAB character too!

commandlinefu gives the correct answer which strips ANSI colours as well as movement commands:

> sed "s,\x1B[[0-9;]*[a-zA-Z],,g"

I managed with the following for my purposes, but this doesn't include all possible ANSI escapes:

sed -r s/\x1b\[[0-9;]*m?//g

This removes m commands, but for all escapes (as commented by @lethalman) use:

sed -r s/\x1b\[[^@-~]*[@-~]//g

Also see "https://stackoverflow.com/questions/7857352/python-regex-to-match-vt100-escape-sequences";.

There is also a table of common escape sequences.

ansi2txt command (part of kbtin package) seems to be doing the job perfectly on Ubuntu.

I don't have enough reputation to add a comment to the answer given by Luke H, but I did want to share the regular expression that I've been using to eliminate all of the ASCII Escape Sequences.

sed -r 's~\x01?(\x1B\(B)?\x1B\[([0-9;]*)?[JKmsu]\x02?~~g'

I've stumbled upon this post when looking for a way to strip extra formatting from man pages. ansifilter did it, but it was far from desired result (for example all previously-bold characters were duplicated, like SSYYNNOOPPSSIISS).

For that task the correct command would be col -bx, for example:

groff -man -Tascii fopen.3 | col -bx > fopen.3.txt

(source)

Why this works: (in response to a comment by @AttRigh)

groff produces bold characters like you would on a typewriter: print a letter, move one character back with backspace (you can't erase text on a typewriter), print the same letter again to make the character more pronounced. So simply omitting backspaces produces "SSYYNNOOPPSSIISS". col -b fixes this by interpreting backspaces correctly, quote from the manual:

> -b Do not output any backspaces, printing only the last character written to each column position.

You can remove all non printable characters with this:

> sed 's/[^[:print:]]//g'

I built vtclean for this. It strips escape sequences using these regular expressions in order (explained in regex.txt):

// handles long-form RGB codes
^\033](\d+);([^\033]+)\033\\

// excludes non-movement/color codes
^\033(\[[^a-zA-Z0-9@\?]+|[\(\)]).

// parses movement and color codes
^\033([\[\]]([\d\?]+)?(;[\d\?]+)*)?(.)`)

It additionally does basic line-edit emulation, so backspace and other movement characters (like left arrow key) are parsed.

Just a note; let's say you have a file like this (such line endings are generated by git remote reports):

echo -e "remote: * 27625a8 (HEAD, master) 1st git commit\x1b[K
remote: \x1b[K
remote: \x1b[K
remote: \x1b[K
remote: \x1b[K
remote: \x1b[K
remote: Current branch master is up to date.\x1b[K" > chartest.txt

In binary, this looks like this:

$ cat chartest.txt | hexdump -C
00000000  72 65 6d 6f 74 65 3a 20  2a 20 32 37 36 32 35 61  |remote: * 27625a|
00000010  38 20 28 48 45 41 44 2c  20 6d 61 73 74 65 72 29  |8 (HEAD, master)|
00000020  20 31 73 74 20 67 69 74  20 63 6f 6d 6d 69 74 1b  | 1st git commit.|
00000030  5b 4b 0a 72 65 6d 6f 74  65 3a 20 1b 5b 4b 0a 72  |[K.remote: .[K.r|
00000040  65 6d 6f 74 65 3a 20 1b  5b 4b 0a 72 65 6d 6f 74  |emote: .[K.remot|
00000050  65 3a 20 1b 5b 4b 0a 72  65 6d 6f 74 65 3a 20 1b  |e: .[K.remote: .|
00000060  5b 4b 0a 72 65 6d 6f 74  65 3a 20 1b 5b 4b 0a 72  |[K.remote: .[K.r|
00000070  65 6d 6f 74 65 3a 20 43  75 72 72 65 6e 74 20 62  |emote: Current b|
00000080  72 61 6e 63 68 20 6d 61  73 74 65 72 20 69 73 20  |ranch master is |
00000090  75 70 20 74 6f 20 64 61  74 65 2e 1b 5b 4b 0a     |up to date..[K.|
0000009f

It is visible that git here adds the sequence 0x1b 0x5b 0x4b before the line ending (0x0a).

Note that - while you can match the 0x1b with a literal format \x1b in sed, you CANNOT do the same for 0x5b, which represents the left square bracket [:

$ cat chartest.txt | sed 's/\x1b\x5b//g' | hexdump -C
sed: -e expression #1, char 13: Invalid regular expression

You might think you can escape the representation with an extra backslash \ - which ends up as \\x5b; but while that "passes" - it doesn't match anything as intended:

$ cat chartest.txt | sed 's/\x1b\\x5b//g' | hexdump -C
00000000  72 65 6d 6f 74 65 3a 20  2a 20 32 37 36 32 35 61  |remote: * 27625a|
00000010  38 20 28 48 45 41 44 2c  20 6d 61 73 74 65 72 29  |8 (HEAD, master)|
00000020  20 31 73 74 20 67 69 74  20 63 6f 6d 6d 69 74 1b  | 1st git commit.|
00000030  5b 4b 0a 72 65 6d 6f 74  65 3a 20 1b 5b 4b 0a 72  |[K.remote: .[K.r|
00000040  65 6d 6f 74 65 3a 20 1b  5b 4b 0a 72 65 6d 6f 74  |emote: .[K.remot|
...

So if you want to match this character, apparently you must write it as escaped left square bracket, that is \[ - the rest of the values can than be entered with escaped \x notation:

$ cat chartest.txt | sed 's/\x1b\[\x4b//g' | hexdump -C
00000000  72 65 6d 6f 74 65 3a 20  2a 20 32 37 36 32 35 61  |remote: * 27625a|
00000010  38 20 28 48 45 41 44 2c  20 6d 61 73 74 65 72 29  |8 (HEAD, master)|
00000020  20 31 73 74 20 67 69 74  20 63 6f 6d 6d 69 74 0a  | 1st git commit.|
00000030  72 65 6d 6f 74 65 3a 20  0a 72 65 6d 6f 74 65 3a  |remote: .remote:|
00000040  20 0a 72 65 6d 6f 74 65  3a 20 0a 72 65 6d 6f 74  | .remote: .remot|
00000050  65 3a 20 0a 72 65 6d 6f  74 65 3a 20 0a 72 65 6d  |e: .remote: .rem|
00000060  6f 74 65 3a 20 43 75 72  72 65 6e 74 20 62 72 61  |ote: Current bra|
00000070  6e 63 68 20 6d 61 73 74  65 72 20 69 73 20 75 70  |nch master is up|
00000080  20 74 6f 20 64 61 74 65  2e 0a                    | to date..|
0000008a

sed based approach without extended regular expressions enabled by -r

sed 's/\x1B\[[0-9;]*[JKmsu]//g'

Tom Hale's answer left unwanted codes, but was a good base to work from. Adding additional filtering cleared out leftover, unwanted codes:

sed -e "s,^[[[(][0-9;?]*[a-zA-Z],,g" \
    -e "s/^[[[][0-9][0-9]*[@]//" \
    -e "s/^[[=0-9]<[^>]*>//" \
    -e "s/^[[)][0-9]//" \
    -e "s/.^H//g" \
    -e "s/^M//g" \
    -e "s/^^H//" \
        file.dirty > file.clean

As this was done on a non-GNU version of sed, where you see ^[, ^H, and ^M, I used Ctrl-V <Esc>, Ctrl-V Ctrl-H, and Ctrl-V Ctrl-M respectively. The ^> is literally a carat (^) and greater-than character, not Ctrl-<.

TERM=xterm was in use at the time.

A bash snippet I've been using for stripping out (at least some) ANSI colors:

shopt -s extglob
while IFS='' read -r line; do
  echo "${line//$'\x1b'\[*([0-9;])[Km]/}"
done

My answer to

https://stackoverflow.com/questions/47933467/what-are-these-weird-ha-urls-jenkins-fills-our-logs-with/

removes all ANSI escape sequences from Jenkins console log files effectively (it also deals with Jenkins-specific URLs which wouldn't be relevant here).

I acknowledge and appreciate the contributions of Marius Gedminas and pyjama from this thread in formulating the ultimate solution.

This simple awk solution worked for me, try this:

str="happy $(tput setaf 1)new$(tput sgr0) year!" #colored text
echo $str | awk '{gsub("(.\\[[0-9]+m|.\\(..\\[m)","",$0)}1' #remove ansi colors