Tagged Questions

Questions about shell scripts, executable files that are interpreted by a shell (bash, zsh, etc.).

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2
votes
1answer
333 views

bash script - need date command variable

I am trying to create a script that will parse the /var/log/secure file for failed login attempts for today's date only and redirect those attempts into a separate file so I can view those attempts ...
2
votes
5answers
224 views

Replace instance of process in place?

I suspect this is not doable just because of the security implications, but here's what I'd like to do. Basically we run a bash shell-script on our CentOS server that calls Program-A (in our case ...
1
vote
3answers
409 views

What does “FILENAME=$(echo $INFILE | grep -oE ”[^/]+$“) ” mean?

FILENAME=$(echo /root/Source/code/script.sh | grep -oE "[^/]+$") I know that it would give me the file name from the file path here as script.sh. But can some one please explain me this?
0
votes
1answer
237 views

How to write simple if condition in ash?

I would like to write a small script that would check every once in a while if I have the internet connection. I would like to run it in crontab on my router where I have ash. I am having a hard ...
0
votes
2answers
30 views

Shell script to format logs

Requirement : I need to write a script to find out for which API the request has been sent but no response received. Given below is an example of the logs i'll be working with. 2014-02-28 ...
2
votes
2answers
200 views

Bash script to signal a concurrently running instance (same script) about a condition and increment counter

Background Here's what I want to achieve. I have a (potentially) long-running process. Now I have locking in place just fine and all is generally in order. However, since this is a scheduled job, ...
1
vote
1answer
82 views

What is the Command to check the history of the command executed which should based on the user who accessed it [closed]

I am looking for the command or script to meet the following requirement. I wanted a history of all the users who connected to my machine and what commands they execute in there session and at which ...
3
votes
5answers
611 views

Quoting and escaping

I have a shell script, the arguments of which are collected in quote as a single argument and passed to a perl script. /usr/local/API/check_api.sh "-D x.x.x.x -C Test_Internal_Cluster -u user -p pass ...
3
votes
2answers
4k views

bash script error: source: not found

I must be missing a fundamental understanding about sourcing files in bash. I've tried the different approaches that seem like they should work, but I still get this error source: not found. In my ...
2
votes
3answers
92 views

How to optimize this oneliner? (if second column empty, put the line in another file)

I have a little "oneliner": while read ONELINE; do if [[ -n "`echo $ONELINE | awk '{print $2}'`" ]]; then echo "$ONELINE" >> LIST-ok.txt else echo "$ONELINE" >> ...
6
votes
7answers
1k views

How to detect the desktop environment in a bash script?

I am writing a bash script that needs to know which desktop environment (XFCE, Unity, KDE, LXDE, Mate, Cinnamon, GNOME2, GNOME3,... ) is running. How can I obtain that information?
1
vote
0answers
49 views

manipulate a Drush “internal” variable

I want to modify a variable (preferably in a Bash Script format) because my PHP environment requires a port number. To show a URL in Drush containing a token that logs you in as user 1 (without a ...
-1
votes
1answer
44 views

growing up with linux scripting and online resource to learn it [closed]

Is learning Linux shell scripting good for developing own career?I use linux and very much interested in scripting. Where should I start from?
0
votes
1answer
52 views

Is it a bad idea to keep scripts in /root? [closed]

Is it a bad idea to keep scripts in /root? Simple bash scripts that have the following permissions: -rw-r--r-- They execute fine when ran as root, but is this bad practice? It's a multi-user system, ...
2
votes
2answers
2k views

Read non-bash variables from a file into bash script

My bash script needs to read the variables from a text file that contains hundreds of variables, most of which conform to standard bash variable sytax (e.g., VAR1=VALUE1). However, a few lines in this ...
3
votes
2answers
318 views

Moving large numbers of files and directories to a different directory

I'm trying to move the following move a large number of files that exist in the following structure to a /mnt/originals but I need to maintain the structure at the same time. I know cp would be a ...
6
votes
3answers
3k views

reliable return code of background process

Let's assume the following piece of bash code: foo > logfile 2>&1 & foo_pid=$! while ps -p$foo_pid do ping -c 1 localhost done wait $foo_pid if [[ $? == 0 ]] then echo "foo ...
3
votes
2answers
921 views

Interactively concatenate video files

Problem : How to concatenate (join) multiple MP4 video files into one file interactively? There are a lot of programs that do this for two files from the command line. For instance : ffmpeg, ...
0
votes
2answers
2k views

Cron job is not working [closed]

i have a cron job center code hereonfigured at var/spool/cron/testuser, Am calling "adindex.sh" file from there. Am getting results when am directly put the command directly in prompt(php and sh), ...
0
votes
1answer
114 views

Combining two bash scripts by adding flags

I have two scripts which transform the code from software v.1 to software v.2 and viceversa. These are essentially a lot of sed substitutions. In the way I wrote them they accept two arguments: ...
1
vote
4answers
1k views

move file by list in file

I have a file the contain filenames, for example: /tmp/list.txt (it is with the spaces at the start of each line): /tmp/file.log /app/nir/home.txt /etc/config.cust I want, using one line, ...
4
votes
3answers
201 views

shell script problem with using the operators

I am comparing two strings using the levenshtein distance algorithm. I got the PHP implementation of the algorithm from here. I am calling this php implementation from my shell script as below. ...
4
votes
2answers
271 views

Dump process's stdin and stdout

I have two processes, let's say Parent and Child. Parent launches the Child and communicates with it through child's stdin and stdout. Parent <-> Child These processes use text protocol and I ...
21
votes
3answers
8k views

If I sudo execute a Bash script file, will all commands inside the Bash script be executed as sudo as well?

I want to write an automated post-installation script in Bash (called post-install.sh, for instance). The script will automatically add and update repositories, install and update packages, edit ...
4
votes
2answers
496 views

Shell Script to isolate files scattered in different folders

I need to write a shell script that traverses a given directory structure in multiple levels, recognizes the video files scattered in the folders and copies all of them to another single folder. The ...
7
votes
1answer
307 views

Parallel execution of bash script

I have a table URL_Experiment in my database (mySQL database). I have 2 million URL links in this table. For each URL, I am checking if some particular text is present in the URL and updating the ...
1
vote
1answer
63 views

what is $# used in a script for? [duplicate]

In many scripts in my organisation and even on online tutorials, this is a common if clause I come across : if [ $# -eq "somethng" -o $# -eq "somethng" ] what does this $# condition ...
-2
votes
1answer
35 views

Implementation Logic [closed]

I have two files,which is something like this: file1 msgid "New" msgstr "" dsvhuvchvdhcvhc msgid "Old" msgstr "hsvhs" kdnvcjdbvj msgid "Bold" msgstr "" file2 dcbjdsbc msgid "New" msgstr "Alas" ...
1
vote
3answers
2k views

Bash script to convert all *flac to *.mp3 with FFmpeg?

I want to convert all *.flac to *.mp3 in the specific folder. This is what I've tried, but not works: # change to the home directory cd ~/music # convert all *.flac files ffmpeg -i *.flac -acodec ...
0
votes
1answer
42 views

Getting a delimiter issue while executing the script

I am creating a test.sh file and i am running it as ./test.sh: string="hello" ed << EOF e any_file 1i ${string} EOF can anybody help me what it does? I am getting some delimiter issue. Can ...
1
vote
2answers
63 views

How can I substitute one command for another temporarily?

I'd like to alias sed to gsed, but only while a particular script is running. I have a script that invokes sed. On the Mac, BSD sed doesn't support the required features, but I don't want to replace ...
0
votes
2answers
70 views

Increment Daily Config Value

I have a configuration file that contains a lookback value, which I need to increment by +1 each day. IE: 60, 61, 62 etc.... It doesn't look like awk will work because of the formatting of the ...
5
votes
1answer
306 views

counting multiple patterns in a single pass with grep?

I've written a grep loop to iteratively count DNA trinucleotides within a gzipped DNA fasta file containing DNA sequences e.g. declare -a tri=(AAA AAC AAG AAT CAA .. etc) for i in ${tri[@]} do ...
2
votes
1answer
91 views

Monitor setup commands do not work in script

I'm running Arch Linux 64-bit on a Samsung RV511. I often connect external monitors using xrandr. As I run LXDE with Awesome as a window manager, I need to prepare the xrandr-command by killing ...
0
votes
0answers
58 views

Shell script use ssh forwarding to send a file to a second system

I have ssh forwarding enabled and ssh to server A. On server A I want to run a script as root and take advantage of the ssh key being forwarded for USER to send a file to system B. I'm getting a ...
1
vote
1answer
87 views

print all values of a file after removing some characters using grep

I have a file in which the values are stored as below. Assistant Professor at SASTRA University St John's memorial college Paul George Univeristy Department Chair at University of Texas I am ...
2
votes
3answers
1k views

Extracting characters after a particular text

I am extracting a page from website using cURL command. curl "www.google.com" -s | w3m -dump -T text/html > foo.txt The w3m command outputs the HTML page in a much more simpler format so that ...
2
votes
1answer
351 views

shell script construct array for file elements

I have a file named input_file which contains some lines. I need to remove certain characters in the line and store them in an array. So to remove the characters, I use the sed command and storing in ...
0
votes
1answer
43 views

Using !n in script or interactive mode

I add to ~/.bashrc the following code: test_exclamation () { printf %s "$READLINE_LINE" | xargs echo } bind -x '"\eX": test_exclamation' I write to bash prompt buffer $ !1700 If I press Enter, ...
1
vote
2answers
84 views

Make Trickle get the correct $PATH

Trickle is a bandwidth limiting program. I have the following script for trickle. #!/bin/bash echo $PATH trickle -s -t 3 -u 200 -d 200 "$@" I have a script in ~/bin/ that want to run the script ...
1
vote
3answers
164 views

Copy command from history to bash prompt

Sometimes I'd like to get some command from history output, copy it to bash prompt, make some changes and run it. Is there a way to copy command from a history output to bash prompt without involving ...
1
vote
1answer
370 views

Basic script in Angstrom Linux running on a Beaglebone Black

On my embedded system, I can toggle a user led with: echo > 1 sys/class/leds/beaglebone:green:usr2/value. Similarly, I can find the value of a GPIO (gpio60) (set to input), with more ...
1
vote
3answers
253 views

Script to split string

@terdon's answer provides this script: find . -type f -name "*mp3" | while read file; do album="$(basename "$(dirname "$file")")"; filename="$(basename "$file")"; ...
2
votes
4answers
92 views

inline conditionals for assignment

Is there an "inline-equivalent" to expressions like the following?: if [[ $VERBOSE == 1 ]]; then V=$FOO else V= fi I'm thinking of something like this in perl, for example: $V = $VERBOSE ? ...
0
votes
2answers
681 views

“Expect” automation tool output to shell variable

#!/bin/bash # more commands here expect << EOD spawn telnet localhost 9151 expect -exact "Trying 127.0.0.1...\r Connected to localhost.\r Escape character is '^]'.\r" send -- "AUTHENTICATE ...
1
vote
3answers
269 views

Where to put wrapper scripts?

I created some scripts for administrative tasks etc, I made them to be independent from environment - every dependency is injected through arguments. However it is annoying to provide to script ...
1
vote
2answers
94 views

How can I tell what device or file name I am redirecting to

From within a shell script (sh/bash), how can I tell what device or file name I am redirecting to? For example, I have a shell script named script.sh. I run the shell script and redirect STDOUT to a ...
1
vote
1answer
53 views

Automatically copy PDF.plugin to Chromium.app

I'm using Chromatic.app to update my Chromium.app recently. I'd like to use Chrome.app's PDF.plugin in Chromium.app. Therefore I need to copy PDF.plugin to the following directory: ...
3
votes
4answers
769 views

Replace all newlines to space except the last

How can I replace all newlines with space except the last newline. I can replace all newline to space using tr but how I can do it with some exceptions?
0
votes
1answer
841 views

shell unexpected end of file error

I had the below script working in a linux machine. page="$(curl http://www.google.com/| grep "title")" if [ -z "$page" ]; then echo "Empty page" else echo "Valid page" fi When am running in ...