I'm working on what should be a very simple BASH script. What I want to do is a pull an image from a webcamera using curl and write it to a file whose name is datestamped.
#! /bin/bash
DATE=$(date +%Y-%m-%d_%H-%M)
DIRECTORY1=home/manager/security_images/Studio_1/
TARGET1=${DIRECTORY1}${DATE}.jpg
curl http://web#192.168.180.211/snapshot.cgi > $TARGET1
When I try to run this I am told that there is no such file or directory. I believe this is due to an error in my escaping but I have tried seemingly every combination of quotation marks around the variables at each stage and still can't get it to work. I just don't understand what is going wrong and could really use some pointers towards what I'm doing wrong.
Many thanks
No, it’s just a typo.
DIRECTORY1=home/manager/security_images/Studio_1/
^^
Should be
DIRECTORY1=/home/manager/security_images/Studio_1/
of course.
As for escaping, even though only safe characters are used now, so quotes are technically superfluous, quoting out all $variables in every line by default is a good habit in shell scripting, there are very few cases when you do not want to use them.
Double quoting the redirection target should be enough:
curl http://web#192.168.180.211/snapshot.cgi > "$TARGET1"
Just make sure the path to it exists. You can run your script with
set -xv
to see how variables are interpolated.
Related
I am writing my own unix scripts so I want to add a new directory for Bash. I add sth in .bash_profile like this.
PATH="~/Documents:${PATH}"
export PATH
and in my ~/Documents, there is a file named test of which the content is
#!/usr/bin/env python3.5
print("hahahhah")
I also used
chmod 755 test
to make it executable.
But I cannot call it in terminal directly. ./test works as usual.
What went wrong?
After I change to
PATH="$HOME/Documents:${PATH}"
export PATH
nothing happens.
FDSM_lhn#9-53:~/Documents$ test
FDSM_lhn#9-53:~/Documents$ ./test
hahahhah
Solution:
The fundamental reason is that I have a command of the same name as default one, So it won't work any way! Changing name will be sufficient!
Tilde doesn't get expanded inside strings. So by quoting the right-hand side of the assignment you prevent it from being expanded and get a literal ~ in your PATH variable which doesn't help you any.
You have two ways to fix this:
Drop the quotes on the assignment (yes this is safe, even for $PATH values with spaces, etc.).
Use $HOME instead of ~.
I prefer the second solution but the first is entirely valid for this case.
Beware though that in places where you aren't doing a straight assignment you often cannot just drop the quotes and trying to use ~ will cause problems.
In which case you will end up finding a question like this with an answer like this and something ugly like this.
I have a shell script that I'm trying to write to a file using multiple variables, but one of them is being ignored.
#!/bin/bash
dir=/folder
name=bob
date=`date +%Y`
command > $dir/$name_$date.ext
The $name is being ignored. How can I fix this?
Have you noticed that the _ was "ignored" as well? That's a big hint.
If you use set -u, you'll see the following:
-bash: name_: unbound variable
The way bash parses it, the underscore is part of the variable name.
There are several ways to fix the problem.
The cleanest is the ${var} construct which separate the variable name from its surroundings.
You can also use quotation in various ways to force the right parsing, e.g.: "$dir/$name""_$date.ext"
And in case your variables might contain spaces (now, or in the future) use quotation for words.
command >"$dir/${name}_$date.ext"
command >"${dir}/${name}_${date}.ext"
Both these are fine, just pick one style and stick to it.
Brand new to KornShell (ksh). I have an absolutely painful and hopefully simple problem.
I need to run a script with a string argument that includes single quotations mark and a variable. In the shell, it looks like this:
run_script -x '*082512*'
And that works fine.
But once I try to run it in a script with a variable for the date, I can not produce those single quotes. I have made the "today's date" variable without problem:
today=$(date "+%m%d%y")
But the problem occurs when I try to run the script. I have tried every possible combination of quotes within quotes and escaping the single quotes etc. etc. to no avail.
Any insight regarding this issue would be appreciated.
commenting here because the formatting is better.
Did you try
today=$(date "+%m%d%y")
run_script -x '*'"$today"'*'
As Glenn Jackman points out, quote are only 'seen' at the first level of shell invocation, where you typed in your command.
If the above doesn't help you, consider editing your question to show exact use case, with exact error messages or other non--expected behavior.
Good luck.
I have a simple script
...
dir=`pwd`
echo $dir
cd ./selenium-grid-1.0.8/
CMD="ant -Dport=$1 -Dhost=$2 -DhubURL=http://172.16.1.137:4444 -Denvironment="$3"-DseleniumArgs="-firefoxProfileTemplate C:/software/rc_user_ffprofile -multiWindow" launch-remote-control"
echo $CMD
$CMD 2>&1
#End
Whenever i run this command, i get: ./register_rc.sh: line 16: C:/software/rc_user_ffprofile: is a directory
this directory has to be an argument to the -firefoxProfileTemplate option. How do i include that in this string without it baffing??
help
thnx
I believe your command should read:
CMD="ant -Dport=$1 -Dhost=$2 -DhubURL=http://172.16.1.137:4444 -Denvironment=\"$3\"-DseleniumArgs=\"-firefoxProfileTemplate C:/software/rc_user_ffprofile -multiWindow\" launch-remote-control"
The backslashes are used to "escape" the quotation marks.
The answers here telling to escape your quotes are wrong. That will pass those quotes directly to ant, I doubt that's what you want.
What's the reason to store the command in a variable? It's a very bad idea. Why can't you just write that command as is? If you want to achieve modularity or code reuse, then define a function.
If you want to display executed commands, use set -x.
Looks like you're mixing your quotes up. Take a look at the syntax highlighting that StackOverflow did for you.
I recommend generating the CMD variable in multiple steps, and make sure you \-escape your quotes.
Alright, I have a script that takes a few arguments, runs data, and then rsyncs the data out to a different server. The problem is that to run the data, I have to take one of the arguments and then run a report using it, which is very bash unfriendly (Ex. [3023.2<>1], [5111.3$]="5", etc).
So if I'm going to run the command, I need to put the argument in single quotes, which would then make the argument not be pulled into it.
Thus if I were to run the script...
arg1 = [5111.3$]="5"
runjob specfile.spx '$arg1'
This wouldn't work, but if I were to run it with double quotes, then there is a good chance that the argument that gets passed in will have double quotes. Any ideas on how to get around this?
Use single quotes around the value when you set it, then use double-quotes around the variable when you expand it:
$ arg1='[5111.3$]="5"'
$ echo "$arg1"
[5111.3$]="5"
Quote escapes. Try
[5111.3$]=\"5\"
The Advanced Scripting Guide has a good section on quoting.