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

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3
votes
2answers
4k views

Remove scientific notation bash script

When I convert MB to GB I'm getting below output. I want this output in normal format. When I use bc I'm getting an error. The text file contains nearly 100 such lines like this. I want to print this ...
3
votes
1answer
141 views

how to deal with arguments when executing a script

how to deal with arguments when executing a script my code is: #!/bin/bash DIR="$1" if [ DIR eq $1 ] then echo -n "total directories:" ; find $DIR -type d | wc -l echo -n "total files:" ; ...
3
votes
5answers
3k views

View a file in a tar archive without extracting it

I want to view the content of the tarred file without extracting it, Scenario: I have a.tar and inside there is a file called ./x/y.txt. I want to view the content of y.txt without actually ...
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 ...
3
votes
5answers
559 views

How can I force a script to use more resources?

I'm running a very time-consuming script which takes many hours to end. Watching top I see that it's only taking 5% of the CPU at best, usually around 3%. Is there any way to force the script to use ...
3
votes
3answers
205 views

Search a directory recursively for files listed in a csv, and copy them to another location

I have a directory (let's call it "Movies") which contains many files and folders. I have a long list of file names in a .csv file (around 4000 entries) which refer to files which are located ...
3
votes
1answer
51 views

Standard/canonical way to test whether foregoing pipeline produced output?

The situation I have in mind has the following structure: % some_command | [PRODUCED OUTPUT] || echo 'no output' >&2 Here [PRODUCED OUTPUT] stands for some as-yet-unspecified testing command,...
3
votes
3answers
3k views

Script to email all matching files in a directory

Trying to set up a bash script to automate sending data files. Desired end result is to check a specified directory once per week, make a list of all Excel files modified within the last 2 days, and ...
3
votes
3answers
6k views

How to get previous year and previous month in solaris 8

How to get previous year and previous month in solaris 8? I have tried below command but none of them is correct: date +'%m' -d 'last month' date +'%Y' -d 'last year'
3
votes
1answer
3k views

bashscript to detect right arrow key being pressed

Why does this always detect as true, even if the keycode is not right-arrow-key? stty_state=`stty -g` stty raw; stty -echo keycode=`dd bs=1 count=1 2>/dev/null` stty "$stty_state" echo $keycode ...
3
votes
3answers
3k views

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.
2
votes
3answers
220 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
2answers
77 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
651 views

Disable Touchpad automatically at startup

I'm running Mint 17 Mate on a new HP250 laptop. I can turn off the touchpad by typing the following from terminal: synclient TouchpadOff=1 Now I want to disable the touchpad automatically each time ...
2
votes
2answers
129 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
votes
4answers
68 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
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=" ...
2
votes
1answer
100 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
688 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
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
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
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 That'...
2
votes
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
votes
2answers
352 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 -...
2
votes
2answers
4k 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
1answer
687 views

Variables in dialog radiolist

I have the following dialog radiolist, which works fine. #!/bin/bash ch1a="1" ch1b="Fri, 20/3/15" ch2a="2" ch2b="Sun, 21/6/15" ch1="\"$ch1a\" \"$ch1b\"" dialog --title "Equinoxes and Solistices" \ ...
1
vote
4answers
62 views

How to gather the name of the files in each subdirectory into a text file in that subdirectory?

I wanted to save the names of all files in each sub directory into a text file in that sub directory, so I wrote this script: #!/bin/bash for X in "$PWD" * do if [ -d "$X" ]; then ...
1
vote
1answer
41 views

How can I edit my bash script to account for whitespace entries? [duplicate]

I made a script to automate ffmpeg conversion from mkv > m4v > open the m4v in Subler.app to import the metadata manually, at which point I'll move the file into my iTunes library. I use iTunes ...
1
vote
2answers
939 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 ...
1
vote
6answers
114 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 ...
1
vote
6answers
3k 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
4answers
116 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 ...
0
votes
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
votes
2answers
93 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
2answers
5k 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??
0
votes
1answer
850 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
votes
3answers
384 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 ...
-1
votes
1answer
107 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
204 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 ...
-4
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
859 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 ...
12
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
384 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 ...
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 ...
10
votes
2answers
689 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? #!/bin/...
9
votes
4answers
5k views

“Friendly” terminal color names in shell scripts?

I'm aware of libraries in languages such as Ruby and Javascript to make colorizing your terminal scripts easier by using color names like "red". But is there something like this for shell scripts in ...
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, ...
9
votes
3answers
799 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
8
votes
0answers
216 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
3answers
463 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 ...