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1
vote
1answer
37 views

Bash: Default variable with command substitution

Is there any way to accomplish the following in one stroke using Bash? my_var=${$(grep -E '^setting_1' /settings.conf):-default_setting1} As opposed to: my_var=$(grep -E '^setting_1' ...
3
votes
1answer
70 views

Append (alter) each array element via parameter expansion (i.e. without printf)?

Let the script below exemplify my quandary.. #!/bin/zsh STUFF=( moose-hoof ovary clydsedale ) echo ${MINE=$(printf "MY-%s " $STUFF)} echo ${MINE_EXP=${STUFF/^/MY-}} MY-moose-hoof MY-ovary ...
6
votes
2answers
392 views

Why do here-documents attempt shell substitution even on a commented line?

I wanted to see how some ASCII art looked in terminal so: $ cat <<EOF ...
1
vote
4answers
36 views

Testing for any of a family of related values in a Bash variable [closed]

Apologies if this has been answered previously, but I couldn't find much online. Here's what I'm trying to accomplish: if [[ "${hostname}" = (foo | bar)servername(01 | 02 | 03) ]]; then ...
2
votes
2answers
33 views

rename of file extension doesnt work [closed]

I'm using code like the following to create a logfile using the shell's string manipulation tools: I have a file name and, in the case of an error, I need to create a log file with the err. Suppose ...
0
votes
1answer
32 views

Imagemagick having trouble escaping shell variables

I have an imagemagick command that is having trouble with the $quote$arcangle and $halfdimension$quote concatenated shell variables I'm passing as strings. Here's the transcript: $> echo convert ...
0
votes
1answer
79 views

Passing a variable argument to egrep in a bash script

I have a script, myScript, which is trying to egrep the script argument in a file. Somehow variable expansion isn't working properly with the egrep command. I believe I've isolated the problem ...
0
votes
2answers
38 views

Find the position of repeated character “&”

How can determine the position of “&” in the column number 5 to substring the value 2 or substring value 3 by awk functions column1|column2|column3|column4|variable1:value1 & ...
2
votes
2answers
104 views

while-loop doesn't seem to remember variable update - no piping involved

I am running LMDE 2 ( 'Betsy') with the standard Mate desktop and I have the following script: #!/bin/bash # This script starts a specified terminal-binary in "Always on Top"-mode # The assumption ...
0
votes
1answer
48 views

Searching path as search pattern in grep command

I have saved the path in the variable . var="/home/myfolder/subfolder" Need to search whether the path in available in a text file using grep. grep -l '${var}' * >abc.txt I'm trying to list ...
0
votes
1answer
79 views

Replace command in Bash script from another script

I'm trying to setup a script that will fetch changes from github where a script has a command that's not executable in Mac OS X. What I'm aiming for is to use sed etc to replace the command within ...
1
vote
3answers
162 views

Is there any way to print value inside variable inside single quote?

Consider I've set variable site and needs to be printed by echo or printf, but If I use single quote to write something and want to use variable then how? Example: $ site=unix.stackexchange.com $ ...
0
votes
1answer
125 views

Jquery like templates for formatting strings in bash

#!/bin/bash rm all for f in assets/css/*.css; do printf "<style type='text/css' >\n" >> all cat $f >> all printf "</style>\n <!-----$f---->" >> all echo "$f ...
0
votes
1answer
92 views

special symbols, . * # inside curly brackets [duplicate]

bash=${BASH_VERSION%.*}; bmajor=${bash%.*}; bminor=${bash#*.} echo "BASH VERSION --- $BASH_VERSION" echo "bmajor ----- $bmajor" echo "bminor ----- $bminor" prints, BASH VERSION --- ...
1
vote
2answers
77 views

Substrings in shell script

Am trying to get a substring from a string but am getting the error: ${curr_rec:3:4}: bad substitution #!/bin/ksh get_file_totals() { if [ -e "$file_name" ] then IFS='' ...
1
vote
2answers
89 views

bash + how to define array variable with instance number

Is it possible to define variable that is called for example machine1 as machine$counter ( while counter=1 ) ? For example, I created the /tmp/config.txt file and set the machine1 as array: $ more ...
2
votes
1answer
188 views

Passing variables to range patterns in awk

I'm trying to use range patterns in awk: grep -a volume somefile | awk '/^Apr 25 23:44:04*/,/^Apr 26 12:44:01*/ {print}' This works fine, but when I try to execute it by putting the date and time ...
2
votes
1answer
47 views

Expand variable in brace expansion [duplicate]

I am trying to enumerate a range of integers using a variable but having some trouble. When I type echo {1..5} I get 1 2 3 4 5 However, when I type a variable, I am unable to get the ...
0
votes
1answer
31 views

need help with inserting variables in a file path on GNU linux (SLES 11)

I am tryin to insert 3 variables to build a path, but unable to get it . I am trying the below log_path="/vol02/logs/$dname/logs/103602_$msname/${msname}_start.log" dname=cfp msname=cfp003 i get ...
4
votes
1answer
70 views

How to make sure the $var variable in expanded in “$varsomething”?

I'm trying to run something like this for n in 1 2 3 4 5 6 7 do run_this_command whatever.$nx$n.in done The files are named as whatever.1x1.in, whatever.2x2.in, ...
3
votes
3answers
2k views

Variable not expanding inside another variable bash

I am reading a csv file in bash script as follows: resource='/data/bscs/' while IFS='|'read seqid fname fpath do echo "FILENO: $seqid" echo "FILENAME: $fname" echo ...
0
votes
2answers
239 views

Expect Scripts - Reading from Files and Accepting User Input

How can I write an "Expect" script to: iterate over a list of IP addresses and log in to each to perform commands (like in a BASH for loop). Right now I just copy/pasted the few lines that are my ...
1
vote
1answer
423 views

awk with variables in condition and in output redirection file

I would please like some help with this command because I didn't find anything in documentation that can cover everything I want. I have some variables that are global, so I would prefer to keep them ...
4
votes
3answers
148 views

Can command substitution be nested in variable substitution?

I would like to use variable substitution on a particular string that I access via a command. For example, if I copy something into my clipboard, I can access it like this. $ xclip -o -selection ...
2
votes
1answer
78 views

Running a constructed command from bash script

I constructed a command like this in a bash script a="my_cmd"; a="$a --verbose"; echo $a; $a; It works and executes my command correctly. But when I add an environment variable to the mix it ...
0
votes
2answers
163 views

Multiple variable expansion modifiers in the same expression

Why does the following idiom not work in bash 4.1.0? if [[ "${FUNCNAME[*]:1/$FUNCNAME/}" != "${FUNCNAME[*]:1}" ]] Here it is in context... function isCircularRef_test () { # ### Seems like ...
2
votes
2answers
90 views

Why does zsh allow name to be null in ${name:-word}?

From zsh documentation: ${name-word} ${name:-word} If name is set, or in the second form is non-null, then substitute its value; otherwise substitute word. In the second form name may ...
2
votes
2answers
29 views

variable substitution in CLI and for loops

I am pretty sure this has been asked already in some form, I just cannot come up with a good find to search it. I want to have a script that do things N times and to which I can pass as a variable ...
2
votes
2answers
611 views

Print file name extension using -exec in find

I am playing around with -exec flag of find command. I am trying to use the flag to print the extension name of files, using a fairly new Linux distribution release. Starting simple, this works: ...
1
vote
3answers
552 views

Variable expansion in Bash

I tried the following commands variable='one|name' echo $variable The output is one|name whereas echo one|name gives an error No command 'name' found. This is reasonable because bash treats | as ...
1
vote
0answers
538 views

bash - expect and variables

I have the followin: while read line; do userinfo=$(echo $line | sed 's/@/,/') IFS=',' read -a address <<< "$userinfo" userid="${address[0]}" domain="${address[1]}" ...
1
vote
1answer
354 views

Bash Brace Expansion & Variables [duplicate]

I have a find command: find Directory/{Alpha,Bravo,Charlie} arg1 arg2 I want to replace Alpha,Bravo,Charlie with $find_dir find Directory/{$find_dir} arg1 arg2 however the latter expands to ...
6
votes
2answers
1k views

Piping bash string manipulation

I've read some other piping bash string manipulation questions but they seem to be specialized applications. Essentially, is there a way to do the below simpler? instead of $ string='hello world'; ...
1
vote
1answer
335 views

Append to PATH-like variable without creating leading colon if unset

I need to append a directory to PKG_CONFIG_PATH. Normally, I would use the standard export PKG_CONFIG_PATH=${PKG_CONFIG_PATH}:$(pyenv prefix)/lib/pkgconfig but PKG_CONFIG_PATH has not been ...
2
votes
2answers
527 views

Environment variable not expanded inside the command line argument

I have a file user-pid.out2 which has "usernumber" and "process id" as two columns. based on usernumber I want to find corresponding process id. the first two lines below does not show the output ...
2
votes
2answers
244 views

assign output of a c program to a shell variable: token error

I have a shell script to run several times a .c program ('switch') which admit 3 input paramenters. I want to run the program 4 times passing values {4,16,32,64}, and for parameters ...
3
votes
1answer
277 views

Service script calls another script with variables

I have a simple service script tomcat7 in /etc/init.d/ to start and stop my app server (tomcat) under the tomcat user. On RHEL6. #!/bin/bash # description: Tomcat Start Stop # processname: tomcat # ...
1
vote
1answer
120 views

Replacing shell variable names in another variable

I've been wrestling with bash variable substitution for a while now and can't figure this out... I have a variable with a command template: CMD_TMPL='sudo -u ${USER_NAME} ${USER_HOME}/script.sh' ...
2
votes
1answer
362 views

Expand shell variable without globbing

I want to check whether an input string refers to a file name - not a wildcard string like *.txt. This doesn't work: if [ -f "$1" ]; Because $1 gets expanded to *.txt, which gets expanded to, say ...
2
votes
1answer
104 views

Parameter substitution and error messages: suppressing line numbers etc

Here is my example file: !/bin/bash # argument-one # Is first argument missing? # First method [[ "$1" == "" ]] && echo "Usage: $(basename $0) filename"; exit 1 # Second method # ...
8
votes
1answer
14k views

Executing commands with ssh and shell script using variables on a remote machine

I'd like to execute a command and script located on a remote machine with a script on a local machine. I know it's possible to execute these kind of commands with ssh, so I made: #!/bin/bash ssh ...
0
votes
1answer
229 views

Copy selected files had subtitutions in name

I have some folders: oldA with A_1.aaa, A_2.aaa, A_1.bbb, A.def, A.ghi oldB with B_1.aaa, B_2.aaa, B_1.bbb, B.def, B.ghi and so on and need to copy them to another folder with selection. I want ...
0
votes
1answer
85 views

Special Parameter query - multiple used to obtain command name? [duplicate]

In a uni text provided us to cover bash scripting, the following variable assignment has got be stumped and I've yet to get an answer back from anyone, hence hopefully someone on here can help. ...
6
votes
3answers
3k views

How can I pass argument stored on a variable to WGET

I'm writing a bash script that extensively uses wget. To define all common parameters in one place I store them on variables. Here's a piece of code: useragent='--user-agent="Mozilla/5.0 (Windows NT ...
3
votes
2answers
635 views

Bash parameter expansion - greedy versus non-greedy

It's a bit of a contrived example but here goes: Say I have a variable 1.2.3.4 containing version information and need to replace the .4 at the end with .5 version=1.2.3.4 echo ${version%.*}.5 ...
3
votes
1answer
1k views

variable expansion within command substitution over SSH bash 4.X

I want to do this ssh ${w100user}@web100 'ls -l "$(grep "${1}" /etc/pure-ftpd/pureftpd.passwd|cut -d':' -f6)"' Which obviously performs an ssh session to server web100 as w100user and then greps ...
-3
votes
1answer
221 views

why does the dollar sign cause this command to be executed?

test_script.sh: #!/bin/sh D1="$(dirname $0)" echo $D1 D0="(dirname $0)" echo $D0 What I type on the command line: $ ./test_script.sh Output: . (dirname ./test_script.sh) What significance ...
3
votes
2answers
337 views

What is the effect of “${(@f)…}” in Zsh?

I ran into a Zsh script and wanted to know its meaning. In the scripts below there is ${$(@f)$(egrep "$2","$file")} expression. From what I searched, @ is to use represent all positional parameters, ...
1
vote
1answer
202 views

Unknown syntax in /etc/rc.d/init.d/functions

Looking at the file /etc/rc.d/init.d/functions, I can see the following is declaring a number of variables as local variables. However, why are the variables killlevel and pid_file have an equal sign ...
1
vote
1answer
48 views

Where can I find documentation on shell script syntax for using a regex within a variable construct?

I'm debugging a shell script (which I didn't write) that contains this loop: read line < "$pid_file" for p in $line ; do [ -z "${p//[0-9]/}" -a -d "/proc/$p" ] && pid="$pid $p" done ...