Strings are typically delimited by quotes, which raises the problem of dealing with strings that include quotes.

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49 views

What is the difference between double quotes (“”) and single quotes ('')? [duplicate]

I really do not know the usage of " and '. I want to know usage of " and '. What is the difference between echo "hi" and echo 'hi'.
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2answers
26 views

When to use bash ANSI C style escape, e.g. $'\n'

I don't use bash often but I recall in the past to pass a tab or newline on the command line I would have to escape the character using the special $ character before a single quoted string. Like ...
8
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4answers
203 views

How to assign space-containing values to variables in bash using eval

I want to dynamically assign values to variables using eval. The following dummy example works: var_name="fruit" var_value="orange" eval $(echo $var_name=$var_value) echo $fruit orange However, ...
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0answers
20 views

Zsh - Modify File Completion w/ Quotes

I've been using Zsh recently, and when I complete a file name within quotes, the completion adds a space after the completed file name. Interestingly, this does not occur when I complete directory ...
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2answers
188 views

Bash string concatenation used to build parameter list

Given this piece of bash: PARMS='-rvu' PARMS+=" --delete --exclude='.git'" echo $PARMS rsync ${PARMS} . ${TARGET} The echo shows the PARMS string as expected, no error is displayed, but rsync ...
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1answer
65 views

Bash script for scp interpreting tilde (~) too soon

So, I just started a new C++ class that requires me to program in a Linux environment. I don't have Linux installed on my machine, but I do have OS X and I can ssh into a linux machine in the lab at ...
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1answer
45 views

Copy newest file in directory over SSH

How might one copy the newest text file from a particular directory on a remote server to his local machine? On the server itself I can do the following: $ cat `cd /home/user/dir ; readlink -f $(ls ...
2
votes
3answers
63 views

Checking if an input number is an integer

I'm trying to check if an input is an integer and I've gone over it a hundred times but don't see the error in this. Alas it does not work, it triggers the if statement for all inputs ...
2
votes
1answer
50 views

How can I pass a filename containing percent signs (%) as a parameter to a shell script in cron? [duplicate]

We have currently setup a cron job for our new script as below: 46 22 * * * /gzm_common/diagbat9/global/prod/chgstatus.sh /backups/diagbat9/Demantra/output/SK_ITEM_EXTRACT_MFGPRO_$(date +%m%d%y).txt ...
2
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2answers
50 views

Replace a backslash with sed

I've been trying to create a script that would replace every occurence of C:\ in two different types of file by /root. My arborescence looks like : - Batch - Place of the script - Conf - Appli1 ...
0
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1answer
37 views

Quote escaping struggle with grep and sed

I'm writing a bash script to extract data from html tags and I found this command in another thread : grep -o '<tr>.*</tr>' HTMLFILE | sed 's/\(<tr>\|<\/tr>\)//g' > NEWFILE, ...
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3answers
229 views

Preventing a specific space from being expanded in a variable

In bash how do you avoid a specific space from being expanded in a variable? Lets say I have this JAVA_OPTS="-Xmx1g" JAVA_OPTS="$JAVA_OPTS -XX:OnError='/path/to/a/script.sh %p'" function args() { ...
4
votes
2answers
51 views

Inconsistent redirection behavior ssh interactive vs commands

These work, ssh remote 'echo hi > hi.txt' echo hi | ssh remote 'cat > hi.txt' but this does not work ssh remote sh -c 'echo hi > hi.txt' I expected to produce a file on remote named ...
16
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5answers
1k views

Parenthesis in bash arithmetic: 3 * (2 + 1)

expr does not seem to like parenthesis (used in mathematics to explicit operator priority): expr 3 * (2 + 1) bash: syntax error near unexpected token `(' How to express operator priority in bash?
4
votes
1answer
188 views

command: ls /etc | sort | grep d* is yielding no results but ls /etc | sort | grep p* lists entire directory

I am playing around with piping and grep tonight. I know that grep uses regex and that * means 0 or more occurrences of the preceding character. So the way I understand it is that if I do the ...
1
vote
1answer
48 views

Handling sed variables with paths in them?

I have an applescript for doing certain things, like search and replace. set lol to quoted form of POSIX path of (choose file with prompt "VälJ Fil") That chooses a file then im doing this set ...
3
votes
5answers
253 views

How to use a shell variable inside sed's s command? [duplicate]

we know that we can get the value of a variable using $ sign: x=3 echo $x 3 Is there other ways that we can use to get the value without using $ sign. I'm asking this because $ sign is a special ...
2
votes
2answers
60 views

How to escape spaces etc in passed variable, for system call to cp in awk

As the title suggests, this problem has enough layers of complexity to make simple escaping characters difficult for me. I have a bash script which, for a large part, has an embedded awk script that ...
2
votes
2answers
97 views

Replace value within single quotes in a line that contains certain word using sed command

I have a line as below in a html file, shahar.push(['remoteUrl', 'staging.zazzercode.com']); Depending upon environment, I want to replace the remoteUrl value with sed command. eg, ...
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0answers
55 views

How to pass multiple commands via pssh and multiple xterms

I'm attempting to open multiple xterms and run a command as an SAP user via sudo using pssh. So far, I'm able to run PSSH to a file of servers with no check for keys, open every xterm in the servers ...
5
votes
1answer
457 views

What does su - `whoami` command do?

I am running a script in my project and I see this command su - `whoami` I am having a few basic questions: What does this command do ? What is the significance of `` quotes outside the whoami ...
3
votes
2answers
33 views

How to build space separated, escaped full paths of files recursively matching glob?

I have a program which requires paths to files as arguments, which cannot be quoted and must not depend on working dir. Can this be done without chaining multiple xargs, tr, find, readlinks? Example ...
2
votes
1answer
64 views

Backslash with pipe in system command from awk

I want to invoke shell command from awk so I am using system() but when I am passing expression in I am getting error at backslash. Here is my expression echo "select * from abc limit 1;"| ...
5
votes
1answer
612 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 ...
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2answers
50 views

Why does passing a HEREDOC as a string to `ruby -e` not work?

For reasons I don't understand, it seems to be impossible to pass a heredoc as an expression to a Ruby interpreter: $ ruby -e <<END heredoc> puts 'hi' heredoc> END ruby: no code ...
3
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2answers
121 views

Add arguments to bash -c

Let say that I want to run a command through bash like this: /bin/bash -c "ls -l" According to bash man page, I could also run it like this: # don't process arguments after this one ...
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1answer
45 views

How could I retain special character without replacing it with underscore?

I'm working on a file transfer script where I encounter a problem, when the file name look like Dr' A. The transfer script will fail due to following error: sftp> put /path/Dr'\ A.tif Unterminated ...
5
votes
1answer
173 views

Test -n gives unexpected result

I understand test -n <expression> to return false if the expression evaluates to a string length of greater than 0. Why then does the following happen? Macbook:~ echo ${#undeclared_variable} 0 ...
1
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1answer
48 views

How to enclose a quoted variable in quotes

I want to call: ./mjpg_streamer -i "./input_uvc.so -r 320x240" -o "./output_http.so -w ./www" from a C program, running system(). The problem is that I have to enclose shell command in quotes, which ...
2
votes
1answer
65 views

Could “>” be included in a bash Variable?

Current approach: sudo awk 'BEGIN{printf "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n<hello>\n\t<world>\n";} {print "\t\t",$0}END{printf "\t </world>\n</hello>\n"}' ...
2
votes
1answer
63 views

Change a specific line using sed

I need to change a line in a Java file called DbConnection.java using the sed command. The line is: connection = DriverManager.getConnection("jdbc:mysql://**localhost**/**bajaj**","**root**", ...
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2answers
92 views

Using exec in find over ssh from shell script

So, I am attempting to execute the following from within a shell script; ssh -q $CUR_HOST "cd $LOGS_DIR; echo cd $LOGS_DIR; find . -name *.log -mmin +1440 -exec gzip {} \; exit" When this runs, it ...
3
votes
2answers
152 views

Variable assigned inside ssh command doesn't return proper value

I'm executing the below command in the ssh part of my script. The command is meant to cut the file size from ls option and storing it to a variable. Then print the variable: echo "Enter srouce file"; ...
1
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2answers
47 views

Problems with basename in a loop

I am new at shell script programming and I'm trying to execute a software that reads a text and perform it's POS tagging. It requires an input and an output, as can be seen in the execute example: $ ...
0
votes
1answer
79 views

How to exit the script in ssh session?

My script contains a ssh command to login to remote server and execute a few commands, The command checks if a file exist and if not it should come out of the entire script. ssh $user@$hostname "if[ ...
0
votes
1answer
146 views

Bash Script : Passing a variable to a bash script that contains quotes, single quotes. etc [closed]

lets assume this is the string: 'a',"b" it contains both single and double quotes. how would you pass this to a bash script as a single string ? this is the bash script: #!/bin/bash echo $1 ...
2
votes
2answers
110 views

“cat” command: how to automatically escape everything that might be a violation?

If you copy the contents of httpd.conf and then paste it into a cat command.. such as this one.. #!/bin/bash cat > /test << EOF pasted here.. EOF you run into this error: -bash: ...
0
votes
2answers
243 views

Running system bash command in PHP script - syntax error: unexpected T_LNUMBER

If anyone can shed some light on my issue that'd be great. Please don't down-vote me; I'm new to the language and the OS itself and I'm trying my best to research before asking questions, so any ...
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0answers
51 views

Why does vim color this .bashrc line incorrectly? Fixable?

I have the following line in my .bashrc that allows me to use rlwrap with sqlplus. Why does vim seem to color this wrong? alias sqlplus='rlwrap -c -f /usr/bin/rlwrap -b ...
2
votes
1answer
95 views

Why is my tar in a script behaving different than using tar manually

I'm writing a backup script for my email and cloud service. For simplicity, I only posted the mail-backup part here. Basically, I have a Host-Machine with some Virtual Boxes running in it. These ...
0
votes
3answers
45 views

How do I match a string with symbols in a grep-kind of way? [duplicate]

I have a file with this contents (or similar): # cat /var/www/htpasswd foo:$apr1$73wJ8tiQ$HdaRYe2pUMqBf0ZpMJz6h/ and I'm trying to verify the presence of an entry in it, by matching it, like this: ...
3
votes
3answers
75 views

Print a string including single quotes and other special characters

How can I write this with an AIX script correctly? My requirement is to write this command in test.txt: clock=$(prtconf -s | awk '{print $4,$5}') I tried this command: print 'clock=$(prtconf -s | ...
0
votes
3answers
68 views

Why doesn't source work when I call bash -c

I want to run a command that sources a script to take on some env. variables before executing, without sourcing them in my current shell. test.env export test=1 None of these commands echo the ...
2
votes
4answers
176 views

How do I pass a variable from my local server to a remote server?

I am trying to pass a variable from my local server (location1) to a remote server (location2). The purpose of the code is to copy a file from the remote server from a predefined location. In simpler ...
3
votes
2answers
171 views

How do I echo an expression with both single and double quotes?

I have tried many things, but I'm new to the shell. Is it possible to have both double and single quotes within an echo? I want to generate echo "scan 'LPV',{FILTER => "(PrefixFilter ...
1
vote
1answer
93 views

grep and command-line variable substitution

In the following command sequence, $ grep -E '^.{11,22}John' emplist Operations John Thompson PARTHawks Cher Sales John Jacobs FULLHawks Davinder Singh Finance ...
20
votes
3answers
1k views

Why does my shell script choke on whitespace or other special characters?

Or, an introductory guide to robust filename handling and other string passing in shell scripts. I wrote a shell script which works well most of the time. But it chokes on some inputs (e.g. on some ...
1
vote
1answer
51 views

Problem in using user defined variable in a script

The following is a simple script, named myscript, that I wrote in order to run a command. dcmpath='$HOME/Data' dcmfile='IM1' dcm2nii $dcmpath/$dcmfile Unfortunately, bash does not recognize the ...
2
votes
1answer
59 views

How do I eval two commands?

If I run this: echo "echo 'a'; echo 'b'" It produces a string which I can then run, and it works - echoes a\nb\n. However, this does not work: $(echo "echo 'a'; echo 'b'") Why not? It doesn't ...
2
votes
1answer
63 views

How to ensure that string interpolated into `sed` substitution escapes all metachars

I have a script that reads a text stream and generates a file of sed commands that is later run with sed -f. The generated sed commands are like: ...