Questions tagged [escape-characters]

Escape sequences such as encodings of terminal commands and function keys

65
votes
11answers
40k views

Removing control chars (including console codes / colours) from script output

I can use the "script" command to record an interactive session at the command line. However, this includes all control characters and colour codes. I can remove control characters (like backspace) ...
61
votes
5answers
158k views

How to escape quotes in shell?

I'm having trouble with escaping characters in bash. I'd like to escape single and double quotes while running a command under a different user. For the purposes of this question let's say I want to ...
41
votes
3answers
23k views

Where do I find a list of terminal key codes to remap shortcuts in bash?

For example: "\e[1;5C" "\e[Z" "\e-1\C-i" I only know bits and pieces, like \e stands for escape and C- for Ctrl, but what are these numbers (1) and letters (Z)? What are the ;, [ and - signs for? ...
30
votes
6answers
25k views

Is there any reason why I get ^[[A when I press up arrow at the console login screen?

Whenever I'm at the console login, I press up arrow intentionally to see the previously typed commands. But I see this ^[[A. But when I press Ctrl Alt Print Screen Scroll Lock Pause Break Page Up ...
35
votes
3answers
2k views

How do some tools (e.g. nano , less) manage to leave no content in terminals after exit? [duplicate]

Whenever I use a pager like less or an editor like nano in the shell (my shell is GNU bash), I see a behaviour I cannot explain completely and which differs to the behaviour I can observe with other ...
9
votes
3answers
1k views

Is there any objective benefit to escape sequences over tput?

In people's '.*rc' files I see online or in various code, I tend to see a lot of people who manually use ANSI escape sequences instead of using tput. I had the understanding that tput is more ...
10
votes
2answers
20k views

Trouble in script with spaces in filename

I've got a script that scp's a file from remote host back to local. Sometimes the file names contain spaces. scp does not like spaces in its file names. For some reason my attempts at handling the ...
62
votes
2answers
83k views

Why does Ctrl-D (EOF) exit the shell?

Are you literally "ending a file" by inputting this escape sequence, i.e. is the interactive shell session is seen as a real file stream by the shell, like any other file stream? If so, which file? ...
3
votes
2answers
11k views

How to escape a single quote? [duplicate]

This works fine: sed -i 's# @driver.find_element(:xpath, "//a\[contains(@href,##' temp_spec.rb against a source of @driver.find_element(:xpath, "//a[contains(@href,'change_district')]").click I ...
7
votes
2answers
2k views

Issue with column command and color escape codes

I'm colorizing the header of a table formatted with column -ts $'\t' Works well without color codes, but when I add color codes to the first line column doesn't properly align the output. Without ...
4
votes
2answers
1k views

Why does “shift-tab” result in “Escape” in the terminal?

I just noticed this by accident. I use the vi readline mode (run set -o vi in bash) so it is particularly noticeable; in emacs readline mode I don't think Esc does anything, but in vi mode it exits ...
112
votes
2answers
9k views

Is Vim immune to copy-paste attack?

You should never paste from web to your terminal. Instead, you should paste to your text editor, check the command and then paste to the terminal. That's OK, but what if Vim is my text editor? Could ...
59
votes
11answers
67k views

How do I clear the Gnome terminal history?

When we use clear command or Ctrl+L in terminal, it clears terminal but we can still scroll back to view the last used commands. Is there a way to completely clear the terminal?
13
votes
2answers
5k views

The difference between \e and ^[

Gilles wrote: character 27 = 033 = 0x1b = ^[ = \e Demizey wrote: ^[ is just a representation of ESCAPE and \e is interpreted as an actual ESCAPE character Then I also found this line from a ...
29
votes
2answers
7k views

How to avoid escape sequence attacks in terminals?

Reading the details of CVE-2009-4487 (which is about the danger of escape sequences in log files) I am a bit surprised. To quote CVE-2009-4487: nginx 0.7.64 writes data to a log file without ...
19
votes
3answers
68k views

Escape sequences with “echo -e” in different shells

I just noticed that it seems like the flag -e does not exist for the echo command in my shell on Linux. Is this just a messed up setting or is it "normal"? Some code as an example: #!/bin/sh echo -e ...
6
votes
2answers
144 views

Question about behavior of control key shortcuts

I am confused about how Ctrl-key combinations work in terminal. In bash man page, there are various combinations such as: C-e - go to end of the line C-f - go one character forward etc. But then ...
6
votes
1answer
5k views

In Bash, why is PROMPT_COMMAND set to something invisible?

On RHEL6 and CentOS 6, /etc/bashrc sets PROMPT_COMMAND here: case $TERM in xterm*) if [ -e /etc/sysconfig/bash-prompt-xterm ]; then PROMPT_COMMAND=/etc/sysconfig/bash-prompt-xterm ...
6
votes
3answers
2k views

Non-printing escape sequence: when?

Recently, I have been playing around a lot with color in the terminal and, therefore, with escape sequences, too. I've read the relevant parts of the Bash manpage along with numerous helpful pages on ...
7
votes
1answer
4k views

How to use less in a script without getting ESC escape characters?

When I use less at the command line the output is like but when I use less from within a bash script I get: How can I use less in a bash script and not get all the escape characters and have it work ...
3
votes
2answers
368 views

Why does 'cal' use weird 08 / ^H / \b terminal code for highlighting and how does that work?

When you run cal on Linux, the output for the current month will reverse video highlight the current day. When I send that output to hexdump -c, I get some interesting results: 0000000 ...
2
votes
2answers
1k views

Strange characters when the output of `ls` is redirected to a file

I want to list the components of the current working directory in a text file ls -1 > textfile Output looks fine with more. 1010661085645 1010729039145 1010747080245 1010849051345 1010859053445 ...
1
vote
4answers
2k views

blink code(escape code) has been removed?

According to Bash tips: Colors and formatting (ANSI/VT100 Control sequences) I attemped to active blink code in my program, But may be blink code has been eliminated. Is it true? If is not true, ...
34
votes
2answers
6k views

Where do my ANSI escape codes go when I pipe to another process? Can I keep them?

I sometime want to pipe the color-coded output fror a process, eg. grep... but when I pipe it to another process, eg. sed, the color codes are lost... Is the some way to keep thes codes intact ? ...
13
votes
1answer
5k views

Caret square bracket square bracket A ^[[A - What does it mean?

Apologies if this has already been asked, but I have no idea how I can find this out myself - when I search for "^[[A" in any search engine it ignores the "^[[" part altogether. Anyway, my question: ...
13
votes
2answers
4k views

How do I background an SSH session? [duplicate]

Possible Duplicate: How can I break away from an SSH session that has crashed? I have started an SSH session on the command line, but now I want to get back to my local command line. For any ...
12
votes
2answers
6k views

How to determine the current color of the console output?

I know that, if a coloured terminal is available, one can colour the output of it using escape characters. But is there a possibility to find out, which colour the output is currently being displayed ...
12
votes
1answer
2k views

Weird symbols on screen when using grep?

Any idea what could be causing this? Without using grep, the only stuff display there are the ISO codes and empty space. Software used Command: ./trans --id --input /path/to/txt | grep ISO | grep [a-...
14
votes
4answers
2k views

Escape sequences in output of script called from ncurses application

I'm currently running mcabber as my Jabber client (which uses ncurses) in a tmux session on my homeserver. Locally i run iTerm2 as a terminal emulator, which supports the triggering of growl ...
12
votes
1answer
15k views

Why do I have to escape a “dot” twice?

I know that we can escape a special character like *(){}$ with \ so as to be considered literals. For example \* or \$ But in case of . I have to do it twice, like \\. otherwise it is considered ...
10
votes
1answer
411 views

Do shells other than Bash and Zsh support ANSI-C quoting? e.g. $'string'

I have a shell script that uses the following to print a green checkmark in its output: col_green="\e[32;01m" col_reset="\e[39;49;00m" echo -e "Done ${col_green}✓${col_reset}" After reading about ...
7
votes
1answer
5k views

Hide and unhide cursor with tput

tput civis successfully hides the cursor. tput cvvis should unhide it, but it doesn't. Any idea what the problem might be?
6
votes
2answers
1k views

Background color whitespace when end of the terminal reached

I am working with control sequences for text formatting and have stumbled upon some unexpected behavior. I have some text to output, in the middle of this text there is some smaller text block ...
6
votes
5answers
13k views

What is the problem with the output of plink?

On my Windows7 machine, I'm traversing to the installed path of PuTTy Application and running: plink <hostname> to connect to my remote Linux host. I see some unrecognized characters in the ...
6
votes
1answer
2k views

Is it possible to do a here-document in one line or echo verbatim?

I often find myself testing out a command (e.g. cat file | awk 'stuff') in the shell and when I'm satisfied with the way it works, I append the command to a script file. Let's say this is the command ...
5
votes
2answers
5k views

Calling bash from sh (dash) with commands read from args, and “Unterminated quoted string”/“unexpected EOF”

Just thought I'd document this: I'm trying something very simple - set env variable in bash, and print it out: $ bash -c "a=1; echo a$a;" a $ bash -c "a=1; echo a\$a;" a1 Now I'd want this same ...
3
votes
1answer
793 views

Is it possible to get a character at terminal cursor using ANSI escape codes?

I know I can move the cursor with the escape codes, and I can also print at the cursor. What I'd like to know is if it is possible to pull the character under the cursor. I tried searching for such a ...
3
votes
1answer
361 views

Understanding escape codes

I'm seeing this in my .bashrc file: PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\ [\033[01;34m\]\w\[\033[00m\]\$ ' and I have absolutely no idea what all those ...
0
votes
1answer
3k views

Shell string escape for command arguments [duplicate]

I'm trying to create "/tmp/pwet/foo bar" with this: DIR="/tmp/pwet/foo bar" ARGS="-p ${DIR}" mkdir $ARGS For integration reasons, I have to keep the ARGS building in 2 steps: ARG = some_options + $...
8
votes
2answers
782 views

DEC ANSI command sequence questions; cursor movement

So I'm writing a terminal emulation (I know, I should just compile putty, etc.) and am at the stage of plodding through vttest to make sure it's right. I'm basing it on the VT102 for now but will add ...
4
votes
1answer
164 views

how to escape “\”in ssh-copy-id?

I'm connected to Ubuntu server that is a member of a corporate Active Directory domain via likewise-open. The users are in the form mydomain\myuser. I can connect to it via ssh, escaping the \ with ...
4
votes
2answers
4k views

Trying to print up down arrow keys

I have this: I read down arrow key abc@abc-ubuntu:~/bashpratice$ read -n 3 key ^[[Babc@abc-ubuntu:~/bashpratice$ I am able to grep for it abc@abc-ubuntu:~/bashpratice$ echo $key | grep '\[' [B ...
4
votes
1answer
6k views

Backspace, del, arrow keys not working with interactive programs in Tilda

I currently run Openbox on a light netinstall of Debian. In Tilda, when I use a program like nslookup or winexe, some of my keys do not work properly. Backspace generates ^? Up generates ^[[A Left ...
3
votes
2answers
3k views

What does [?1049h and [?1h ANSI escape sequences do?

When I used shell in a box and when I call less command (echo foo | less) in ajax response there was this code: \u001B[?1049h\u001B[?1h\u001B=\rfoo\r\n\u001B[7m(END)\u001B[27m\u001B[K what does \...
2
votes
1answer
339 views

Modifying a set of binary files

I have several binary files with the character 0x04 in them, and I'd like to add an escape \ character before each. Is there a script I can use to do this without needing to manually edit each one?
2
votes
1answer
998 views

Why i can't send escape sequences from keyboard, but can do it from another tty?

I am trying understand how terminal work, doing different tricks, like writing from one tty to another, changing settings tty1 from tty2, etc. Also, I try this stuff - change color by escape sequence ...
1
vote
1answer
220 views

ANSI escapes in Pash prompt are displayed as garbage in Gnome terminal

I would like to use Pash, a PowerShell implementation for mono on my CentOS box. After compilation I started it and got $ mono Source/PashConsole/bin/Debug/Pash.exe [%?%p1%{8}%<%t37%e%p1%{16}%<...
1
vote
2answers
323 views

How can a bash script detect support for window titling escape characters?

I have a debug trap that runs every time I enter a command in bash that sets the window title to indicate what command is running. I'm leaving out all the configuration details and boil it down to: ...
0
votes
1answer
548 views

Can I get my iTerm key-combos working in tmux?

I have some shortcut keys defined in iTerm, and I use them for key-mappings in Vim. For example, I map Ctrl-Enter to send a ^[O2P escape code, which I then use to define a Ctrl-Enter key-mapping in ...
0
votes
2answers
642 views

Print out binary data as is without breaking the terminal

I've written a Python module to dump objects. When using it with objects that hold binary data (e.g. numpy.ndarray) in a linux terminal (TERM=linux) though, printing out the data results in the ...