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

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How to convert all .wav files in subdirectories to .aac using neroAacEnc?

I have a collection of music in .wav format, and would like to convert it to .aac/.mp4 using neroAacEnc. How do I do this? I am using Arch Linux x86_64 and Xterm.
3
votes
1answer
3k views

How to move file based on file name expression using shell script?

I want to achieve the following using a shell script. When a script is called with a file as a parameter, it should move the file based on a portion of its name. For example, "Car insurance ...
2
votes
0answers
55 views

bash script autobeautifiying using declare -f

I am trying to "beautify" scripts automatically by using declare -f function In a nutshell: Given a bash script foo , you can apparently "automagically" indent it by doing, in bash: MAGIC () { ...
2
votes
4answers
60 views

move a file that matches a pattern in a shell script

I have very little experience in writing shell scripts and need advice on how I can accomplish the following task. I need to move the most recent file in a directory where the filename matches a ...
2
votes
2answers
66 views

Find and replace all same files between 2 directories

I want to find all files in dir1 having corresponding same file names in dir2, and replace them with the files from dir2. For example: dir1: first.txt second.txt dir2: third.txt first.txt So I ...
2
votes
1answer
92 views

Stable timing for shell scripts?

The run times of scripts vary quite much. I would like to find similar time -function as Matlab's timeit, described here. For instance, I am evaluating these commands here about counting quickly ...
2
votes
2answers
334 views

How do you construct a grep & command to match a number of patterns depending on how many are provided at runtime?

I have exported some MS Word documents to plain text and use this function to parse the contents of the .txt files in the current directory: mo1 () { for i in *.txt; do echo "File: $i" grep ...
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votes
3answers
4k 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
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1answer
4k views

“stdin: is not a tty” mails for running scripts as cron jobs

I have several shell scripts (bash) which are started by cron. Every time a script is executed I get an email saying "stdin: is not a tty". Can someone please tell me how to fix this? All scripts run ...
2
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1answer
1k views

Linux nuisance: /dev/stdin doesn't work with sockets

Linux has this blitheringly annoying peculiarity that /dev/stdin won't work with sockets - it is hardcoded to return ENXIO. Try this: socat TCP-OPEN:localhost:1234 EXEC:cat\ /dev/stdin,nofork ...
2
votes
3answers
209 views

How can i get five seconds of data appended to the end of file?

suppose if a shell script appends a data to a file.txt like 1........... 2........... 3............. 4............. 5.............. Now i want another script that could check the fresh data ...
2
votes
4answers
8k views

Match multiple regular expressions from a single file using awk

I'm trying to parse a HTML file using shell scripting. There are 4 different regular expressions that i need to catch: name= , age= , class= , marks=. Using grep "name=\|age=\|class=\|marks=" ...
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votes
2answers
2k views

how to add line in a /etc/sudoers file with the help of shell script (50servers)?

Anyone can help me with shell script, I want to know script which can edit /etc/sudoers file and let me add {{{{{userid ALL=(root) ALL}}}} to 50 server I have on same network?
2
votes
2answers
127 views

how to count number of differences in large streams quickly?

I want to count the number of differences (different bytes) in two large streams (devices/files). E.g. two hard disks, or one hard disk and /dev/zero. The program(s) involved must be fast, as fast ...
2
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3answers
8k views

Bash script; optimization of processing speed

I was wondering if there are general guidelines for optimizing bash script. a) For example, it is more convenient to write loops than lines of commands, but is it also faster to process for the ...
2
votes
3answers
1k views

What's the best way to backup files via network on Linux and Solaris machines?

I wonder what the best way to backup files VIA network I have Solaris machines with Oracle 10i with VERITAS cluster, machines are connected to EMC storage /data/oracle directory is mounted on the ...
2
votes
2answers
605 views

Distributing thousands of files over subfolders

I have a folder A with hundreds of thousands of files. I would like to move these files to new subfolders S_i, with, say, 100 files in each (the last folder may have less than 100 files) In other ...
2
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2answers
3k views

Concatenate multiple files under subdirectories

My directory structure is given below x:\Project_2012-158A\Sample_4041 SampleSheet.csv 4041_CGTACG_L002_R1_001.fastq 4041_CGTACG_L002_R2_001.fastq 4041_CGTACG_L006_R2_001.fastq ...
1
vote
4answers
105 views

Find and delete all same files (by name) between 2 directories

I want to find all files in dir1 having corresponding same file names in dir2, and delete them from dir1. For example: dir1: first.txt second.txt dir2: third.txt first.txt So I want to remove from ...
1
vote
3answers
85 views

Random sampling and outputting the largest value

I have a fairly large data set ~500 million rows. The data set looks like below. Col 1 is float number, col 2 is mac id(device id) 1616.93,ac:22:0b:a6:22:c3 2872.32,c0:bd:d1:36:bb:49 ...
1
vote
6answers
111 views

How can I pass an environment variable to a script?

Okay, I can display an environmental variable from the commandline: echo $COLUMNS And get a response. But I can't execute that from within a shell script, I get nothing. So, there must be a way to ...
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6answers
2k views

Print numbers from 1-50

x=1 while [ $x -le 50 ] do echo $x $x=(($x + 1)) done I have wrote the above code. What seems to be a easy task in many programming languages is giving this error for me. solution.sh: line ...
1
vote
2answers
876 views

Command/scripts to check the Reverse DNS Lookup time

I am working on a project in which one master communicates with numbers of slaves. For that it has to make connection with hosts in network. But sometimes it hangs. I think that the reason behind is ...
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0answers
68 views

!-2 not found when using alias [duplicate]

I'm lazy, so I like to make a LOT of aliases for some of my most common shell commands. I use the command sudo !! quite a bit to tack on sudo for root access, but when I use the following in my ...
0
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2answers
71 views

init.d script not working - trying to launch ssh tunnel in background

trying to get a simple file to run at boot. But's not launching. It works if I run it, but, never at launch. This is my init.d script, launch_ssh_daemon.sh: #!/bin/bash ### BEGIN INIT INFO # ...
0
votes
3answers
343 views

How to loop through lines in a file which contains * in each line

I have a file that contains about 800 lines. All the lines contains 1 * character in it. I need to loop through the lines in the file so I used the following simple for loop for i in $(cat ...
0
votes
2answers
5k views

How do run MYSQL scripts from a shell script with bash variables?

Im making a script where I connect to a database, look for a value and then if that value returned something then I will do something else. ip=$("variable is defined here") Then I connect to the ...
0
votes
1answer
801 views

difficalty to save traceroute output in shell variable?

I need to filter and store traceroute output in shell variable (array). But I am getting some unusual output. As I try to explain in following lines. My present directory is temp, having some ...
0
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2answers
4k views

Is a shell script is a programming Language [closed]

This is the first question in UNIX: I was started shell script from 2 days before. But I have a conflict: is a shell script a special programming language for a specific shell??
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votes
1answer
101 views

Debug an open-source and be confronted with some troubles [closed]

Here is main script . I run it and get some errors like this : ╭─frankwang@ubuntu ~/ion-open-source ╰─➤ ./ionadmin ...
-3
votes
1answer
194 views

SSH with no password

I have a Shell bash file that i run as sudo and it contains a file to send a ssh comand to bulk clients but it asks for the password every time and i do not what key based ssh the password is the same ...
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votes
2answers
1k views

“bash: [: : integer expression expected” [closed]

I want this function to return one random word if there aren't any command-line arguments. I am modifying linuxconfig.org's random-word generator to run even when #$ -ne 1. function random-word { ...
21
votes
2answers
848 views

Why escape trivial characters in shell script?

I just opened a legacy shell script (written in old ksh88 on Solaris) and found the following repeated all throughout the code: [ -f $myfile ] && \rm -f $myfile The escaping backslash ...
11
votes
7answers
4k views

Shortest way to extract last 3 characters of base (minus suffix) filename

I'm trying to set a variable in an sh script to the last 3 characters of the base name of a file (by base name I mean without the path and without the suffix). I've succeeded in doing this but, purely ...
11
votes
2answers
2k views

Suppress output unless non-zero exit code

What's the best way to suppress output (stdout and stderr) unless the program exits with a non-zero code? I'm thinking: quiet_success() { file=$(mktemp) if ! ( "$@" > "$file" 2>&1 ); ...
11
votes
2answers
358 views

How to start tailing a file that has not been yet created

I use tail to monitor the progress of jobs that I know will write their progress to disk. Almost always, I know which file they will create before they start running (the jobs are dispatched by a ...
10
votes
2answers
637 views

Having a problem with a shell script counting characters

I'm trying to learn the basics and I have run into an issue with my script counting the characters of a user's input. Here is my script, can someone point out where I'm going wrong please? ...
9
votes
3answers
722 views

how to check the format of a filesystem

I would like to check, in a bash script, on what filesystem type a directory is. The idea is something like if [path] is on a [filesystem] filesystem then filesystem specific command end if
9
votes
2answers
2k views

How to non-invasively test for write access to a file?

In a shell script, how do I easily and non-invasively test for write access to a file without actually attempting to modify the file? I could parse the output of stat, but that seems really complex, ...
8
votes
3answers
450 views

Extract text between three single quotes

I have the following in a file description: ''' This rule forbids throwing string literals or interpolations. While JavaScript (and CoffeeScript by extension) allow any expression to ...
8
votes
0answers
215 views

how to get exit status from the command before the last [duplicate]

I have solaris machine ( solaris 10 ) please Look on the following simple commands (haconf -makerw | grep -iq "Cluster already writable") # haconf -makerw VCS WARNING V-16-1-10364 Cluster ...
8
votes
2answers
2k views

Find all files with a Python Shebang

I'm trying to run a PEP8 check against a large source tree. The tree is comprised of a mix of files in various languages. The idea is to check all the Python scripts without having to explicitly list ...
7
votes
5answers
603 views

List out strings which are substrings of other strings in the list

I have a list of names like so: dog_bone dog_collar dragon cool_dragon lion lion_trainer dog I need to extract out names that appear in other names like so: dragon lion dog I looked through the ...
7
votes
1answer
5k views

How to strip color codes out of stdout and pipe to file and stdout

I have a program that uses printf with some tput mixed in it and I'd like to pipe the output to stdout as well as a file. I'd prefer to use sed since I don't want any unnecessary dependencies on my ...
6
votes
3answers
489 views

Weird float rounding behavior with printf

I've read some answers on this site and found the printf rounding desirable. However when I used it in practice, a subtle bug led me to the following behavior: $ echo 197.5 | xargs printf '%.0f' 198 ...
6
votes
4answers
545 views

Converting `for file in` to `find` so that my script can apply recursively

I've been working on my first bash script for some time now (I just started UNIX this week). I have this idea of running a bash script to check some conditions and using ffmpeg to convert all the ...
6
votes
1answer
4k 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 ...
6
votes
3answers
7k views

How to get subshell's PID in Korn Shell (equivalent of $BASHPID)

In bash you have this handy variable: $BASHPID wich always returns the currently running subshell's PID. How can I get a subshell's PID in ksh? For example see the code below: #!/usr/bin/ksh93 echo ...
6
votes
7answers
4k views

How do I configure mutt to display the date header in my local time zone in the pager?

When I view a message in the pager mutt displays the time in the Date header in UTC rather than my local time zone. The index view displays the local time correctly. I found this old mailing list post ...
6
votes
1answer
3k views

Recursively compare directory contents by name, ignoring file extensions

I have a directory containing about 7,000 music files. I used lame to recursively re-encode all files in it to a separate directory, outputting all files with the same relative path and file name. ...