I would like to write the $ symbol in a shell script.
I use echo for doing it, but now I need that special character in order to load
the text file and compute a plot modifying the columns in gnuplot
Thanks in advance,
Adrian
try using "\$" instead of "$", escape the character $
Related
The following simplified version of a script I'll call logit obviously just appends everything but $1 in a text file, so I can keep track of time like this:
$ logit Started work on default theme
But bash expansion gets confused by quotes of any kind. What I'd like is to do things like
$ logit Don't forget a dark mode
But when that happens of course shell expansion rules cause a burp:
quote>
I know this works:
# Yeah yeah I can enclose it in quotes but I'd prefer not to
$ logit "Don't forget a dark mode"
Is there any way to somehow collect the remainder of the command line before bash gets to it, without having to use quotes around my command line?
Here's a minimal working version of the script.
#!/bin/bash
log_file=~/log.txt
now=$(date +"%T %r")
echo "${now} ${#:1}" >> $log_file
Is there any way to somehow collect the remainder of the command line before bash gets to it, without having to use quotes around my command line?
No. There is no "before bash gets into it" time. Bash reads the input you are typing, Bash parses the input you are typing, there is nothing in between or "before". There is only Bash.
You can: use a different shell or write your own. Note that quotes parsing like in shell is very common, you may consider that it could be better for you to understand and get used to it.
you can use a backslash "\" before the single quote
$ logit Don\'t forget a dark mode
We have an application that keeps some info in an encrypted file. To edit the file we have to put the text editor name in an environment variable in bash, for example, EDITOR=vi. Then we run the application and it opens the decrypted file in vi. I am trying to come up with a bash script that updates the encrypted file. The only solution that I can think of is passing sed command instead of vi to the EDITOR variable. It works perfectly for something like EDITOR='sed -i s#aaaa#bbbb#'.
Problem starts when I need space and regular expression. For example: EDITOR='sed -i -r "s#^(\s*masterkey: )(.*)#\1xxxxx#"' which return error. I tried running the EDITOR in bash with $EDITOR test.txt and I can see the problem. It doesn't like double quotes and space between them so I added a backslash before the double quotes and \s instead of space. Now it says unterminated address regex. For several hours I googled and couldn't find any solution. I tried replacing single quotes with double quotes and vice versa and everything that I could find on the internet but no luck.
How can I escape and which characters should I escape here?
Update:
Maybe if I explain the whole situation somebody could suggest an alternative solution. There is an application written by Ruby and it is inside a container. Ruby application has a secret_key_base for production and we supposed to change the key with EDITOR=vi rails credentials:edit --environment=production. I don't know Ruby and google did not return any ruby solution for automation so I could only think about sending sed instead of vi to Ruby.
How can I escape and which characters should I escape here?
That is not possible. Word splitting on the result of expansion cannot be escaped from inside the result of that expansion, it will always run. Note that filename expansion is also running over the result of the expansion.
Create an executable file with the script content and set EDITOR to it.
You could export a bash shell function, after some tries I got to:
myeditor() {
sed -i -E 's#^(\s*masterkey: )(.*)#\1xxxxx#' "$#"
}
export -f myeditor
EDITOR='bash -c "$#" _ myeditor'
I have a shell script that need to use a variable following a dash to generate the file names.Here is what I did:
var="5"
echo "filename$var_something.txt"
However, it always output error, because the script treats $var_something as a variable.
How can I solve this?
Thanks.
echo "filename${var}_something.txt" use braces to delimit your variable name.
Hopefully this should be a simple one... Here is my test.sh file:
#!/bin/bash
patch_file="/home/my dir/vtk.patch"
cmd="svn up \"$patch_file\""
$cmd
Note the space in "my dir". When I execute it,
$ ./test.sh
Skipped '"/home/my'
Skipped 'dir/vtk.patch"'
I have no idea how to accommodate the space in the variable and still execute the command. But executing this the following on the bash shell works without problem.
$ svn up "/home/my dir/vtk.patch" #WORKS!!!
Any suggestions will be greatly appreciated! I am using the bash from cygwin on windows.
Use eval $cmd, instead of plain $cmd
Did you try escaping the space?
As a rule UNIX shells don't like non-standard characters in file names or folder names. The normal way of handling this is to escape the offending character. Try:
patch_file="/home/my\ dir/vtk.patch"
Note the backslash.
I'm using perl on windows and am trying to do a one liner using perl to substitute a placeholder in a file using a windows variable that contains a dollar sign. Does anyone know what the correct usage is to make it work with the dollar sign. I've tried various ways and can't seem to get it to work.
For example, I have a properties file that has a token in it (!MYPASSWORD!) that I'm trying to replace like:
somevalue="!MYPASSWORD!"
I have a batch file that looks up a variable say called NEWPASSWORD that contains the password $abc12345$ and I want to use perl substitution to replace the value like the following. Note I may not always know where the $ signs are so I cant escape them. For example another password may be abc$124$563:
echo %NEWPASSWORD% <-- this would contain $abc12345$
perl -p -i.bak -e "s/!MYPASSWORD!/%NEWPASSWORD%/g" a.properties
When its done I want a.properties to be :
somevalue="$abc12345$"
Thanks in advance
Use ' as regexp delimeter symbol. It will disable all variable substitution:
perl -p -i.bak -e "s'!MYPASSWORD!'%NEWPASSWORD%'g" a.properties
I presume you are getting password from user input. why not just do that in Perl without having to go through batch since you are already using Perl? Its easier. you can then use modules like Term::Inkey to mask password and stuff.
simply use escape before dollar, like that :
\$