Questions about bash only, as opposed to other Bourne/POSIX shells. For all Bourne/POSIX-style shells, use the /shell tag instead.

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1
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3answers
62 views

Difference between sh -x and ./ for script execution

So I have a simple shell script. What is the difference between the two commands in execution? Is there a preferred way? $sh -x foobar.sh OR $ ./foobar.sh I found the script executed slower when ...
5
votes
2answers
174 views

Bash displays international characters as escape sequences

When I press certain keys (e.g. German umlauts) in the bash command line, I get escape sequences. For example, ß gives me \303. These escape sequences are treated as single characters, so one ...
0
votes
2answers
34 views

Getting error with sleep and argument in sh script [closed]

I'm doing something like this #!/bin/bash END=3 time_w = 1 for ((i=1;i<=END;i++)); do # do something sleep time_w done but I'm getting sleep: invalid time interval ‘time_w’
13
votes
3answers
8k views

How to check if pipe is empty

I have piped line in bash script and want to check if pipe has data, before feeding program Searching I found about test -t 0 but it doesn't work here. Always returns false. So how to be sure that ...
0
votes
2answers
43 views

How can I break out of a while loop, from within a nested case statement? [closed]

In the script below - which prompts the user to confirm that they want to proceed with running a potentially bad script - when the user enters Y at the prompt - it will break out of the case block, ...
4
votes
0answers
29 views

Search history from multiple bash session only when Ctrl + R is used, not when arrow keys are used

I usually have multiple bash sessions open. I want the history from multiple session to appear when doing a search (with Ctrl + R). When arrow keys are used only the current bash session's history ...
10
votes
7answers
3k views

A bash function that takes argument like other languages?

I have a bash function to set the $PATH like this -- assign-path() { str=$1 # if the $PATH is empty, assign it directly. if [ -z $PATH ]; then PATH=$str; # if the $PATH does ...
0
votes
1answer
33 views

How to ignore spaces in file path for bash select statement [duplicate]

I have the following Bash Script: #!/bin/bash cd ~/Library/Developer/CoreSimulator/Devices/; files=$(find . -name iaGambro_gambro.sql) select file in $files; do if [ -n "$files" ]; then ...
46
votes
9answers
62k views

Looping through files with spaces in the names?

I wrote the following script to diff the outputs of two directores with all the same files in them as such: #!/bin/bash for file in `find . -name "*.csv"` do echo "file = $file"; diff ...
0
votes
1answer
41 views

List all file extensions in an arborescence and count number of occurences of each [duplicate]

I am looking for a simple shell function (bash prefered) to list all file extensions in an arborescence and count the number of occurences of each. For example, list_extensions . would return ...
7
votes
1answer
3k views

Why does redirection (>) not work sometimes but appending (>>) does?

While studying for the RHCE, I came across a situation where stdin redirection does not work in bash: # file /tmp/users.txt /tmp/users.txt: cannot open `/tmp/users.txt' (No such file or directory) ...
-1
votes
2answers
29 views

How to use pass filename without extension to gedit external tool for make?

I am wanting to build and run a program called dbgen using the external tools. I know that this variable holds the filename, ‍‍‍‍‍‍‍‍‍dbgen.c‍‍ : $GEDIT_CURRENT_DOCUMENT_NAME How do I remove the .c ...
7
votes
2answers
7k views

Is it possible for nohup to write the output both to the file nohup.out AND to the screen/terminal?

I am using the bash shell. I frequently use nohup to ensure that my processes are not stopped when I close the shell/terminal that started them. I use a syntax like: nohup myprocess When ...
16
votes
6answers
59k views

How can I read line by line from a variable in bash?

I have a variable which contains multiline output of a command. What's the most effecient way to read the output line by line from the variable? For example: jobs="$(jobs)" if [ "$jobs" ]; then ...
0
votes
1answer
20 views

How can I match and substitute this multiline pattern in a bash script?

I have a file jail.local and it has sections like this [apache] enabled = true logpath = /var/log/apache/error.log [ssh] enabled = false port = ssh I want to match on the string [ssh] and ...
12
votes
6answers
5k views

Is it recommended to use zsh instead of bash scripts?

Can I assume that enough people have zsh installed to run scripts with a #!/usr/bin/env zsh as shebang? Or will this make my scripts un-runnable on too many systems? Clarification: I’m interested ...
4
votes
3answers
855 views

Why read works if stdin is redirected to fd4?

What does the following script mean? exec 4<&0 0</etc/XX/cfg read line1 exec 0<&4 It redirects fd0 to fd4, and "/etc/XX/cfg" to fd0. So why does read still work, shouldn't that ...
2
votes
2answers
72 views

How is IFS really rendered?

I've read bash manpage and other docs, but I find the explanation a bit confusing. I have the following simple script: #!/bin/bash IFS="" echo $2 var=A B C echo $var if I execute it, eg: ...
0
votes
0answers
38 views

Using brew: curl version error, “Incompatible library version” for libcurl.4.dylib

I used to have a working version of homebrew but then something broke today related to curl and libcurl.4.dylib— possibly a version or file location issue. I'm on Mac OS X 10.9.5 (Mavericks). For ...
0
votes
1answer
53 views

How can I populate an array in Bash Shell script loop

cmdline> ls -la /.myScript.sh set index=0 set usrlist[index]="null" while read line do #Total lines read z=`echo $line| wc -l` lines=`expr ...
5
votes
3answers
82 views

How to undo changes in the commands-history?

In UNIX systems you can press top and bottom arrows to navigate through the previous commands. This is extremely handy. Sometimes, I go up and find a command that I want to use again, but with some ...
-1
votes
1answer
59 views

what is shell script? [closed]

Is that some thing like a programming language? Which does provide this option(facility) by a program running on linux or basic program that comes with linux kernel?
0
votes
1answer
54 views

How can I use sed to print out unique users [closed]

I wish to print out the unique users in the system using only sed, using: ls -la | sed '/^$USER$/p' .... It gives me all files, matching to the current user, and prints out the lines they are in. ...
8
votes
3answers
746 views

Escape sequences in output of script called from ncurses application

I'm currently running mcabber as my Jabber client (which uses ncurses) in a tmux session on my homeserver. Locally i run iTerm2 as a terminal emulator, which supports the triggering of growl ...
2
votes
1answer
48 views

Execute commands from history that match regex or grep

I was wondering if its possible to execute commands from history that match a certain regex? I know you can do something like fc 232 248 And it will go into your history and then do revisions ...
2
votes
1answer
119 views

bash time with nohup

I want to know how much time it takes to run something in nohup. I know this works: $ time sleep 2 real 0m2.001s user 0m0.000s sys 0m0.001s But why it doesn't work with nohup? $ nohup ...
9
votes
8answers
11k views

Is there a way to make “mv” fail silently?

A command like mv foo* ~/bar/ produces this message in stderr if there are no files matching foo*. mv: cannot stat `foo*': No such file or directory However, in the script I'm working on that case ...
1
vote
1answer
42 views

Script executes differently if run from udev

I'm having an issue with a script that seems really weird; it appears to stop executing prematurely when run from udev, but not when I run it manually from the command line. I've tried troubleshooting ...
0
votes
1answer
23 views

Filtering Log Output on Separate Lines

I did a recursive grep in a directory to find all files that would match as follows grep -ER "match_string1|match_string2" /path/to/dir/ What I get as output is: ...
0
votes
1answer
41 views

run -i vs run -it?

I am using boot2docker on windows. I tried the following commands docker run -i centos /bin/bash docker run -it centos /bin/bash Both provides same kind of execution. I read -i is interactive ...
0
votes
1answer
132 views

Why isn't this `expr … | bc -l` command working?

I'm noticing an error: bash: syntax error near unexpected token `-105.5*7+50*3' When executing the below script/expression: expr (-105.5*7+50*3)/20 + (19^2)/7 | bc -l Is there any other way ...
0
votes
1answer
34 views

doubts in file system hierarchy? [duplicate]

explain the difference between /bin and /usr/bin used in Linux?
0
votes
0answers
39 views

include Forking - Multi threading in bash script to run it in upstart?

I have lack of understanding. Do i need to include forking in my bash script: http://stackoverflow.com/a/26756839/4749164, so i can use expect daemon/fork - option in upstart? i would like to run my ...
2
votes
2answers
33 views

universal help/man command: help builtin partial matches

I found a nice little script which iterates through a couple of manuals for a specific command. As a last resort, it will Google it and open a browser window. Source here: ...
0
votes
1answer
49 views

What's the best way to make a bash function in a script as a parameter when running via command line?

I'm fairly new to bash scripting, and wondered what's the simplest way to make bash script functions in a script as the parameter when run via command line? Example usage: ./myscript function1 ...
0
votes
1answer
47 views

Log output from more than one script

I have a problem concerning the logging of a process: I have 3 scripts, a.py, b.py and c.sh a.py calls b.py and b.py calls c.sh The goal is to continuously log std out/err (write to file and ...
6
votes
2answers
75 views

How to check from bash if package exists in debian

I would like to make a installation bash script, where I would like to install mysql server. On linux mint I had followed code: apt-get -y --force-yes install mysql-server-5.6 but I installed new ...
0
votes
2answers
65 views

How to use 3rd variable in BASH for loop?

Good day. I want to parse data of particular columns from several files(aprilPlate.txt, mayPlate.txt, junePlate.txt, julyPlate.txt, augustPlate.txt) using For loop. The data of input files ...
1
vote
1answer
47 views

How can I prepending a character for every output of a command?

I'm running commands which I want to specifically group them by every command, as shown in the example below. Tried printing with echo -e '| $line' but it only affects commands that output the text ...
0
votes
1answer
5k views

rsh shows “poll: protocol failure in circuit setup”, why?

In the starting rsh worked properly, but after making some changes it shows some error [changes are shown in the end of this question, see that], I am sharing the same. Command $ /usr/bin/rsh ...
1
vote
2answers
2k views

How do I run two ongoing processes at once in linux/bash?

I would like to know how I can run two ongoing processes at the same time in Linux/bash. basically, I have a Node web server, and a MJPG-Streamer server. I want to run both these processes at once, ...
0
votes
2answers
43 views

How to grep from command line for theses multiple strings?

I need to run a command to grep one of these strings from command line as web host disabled account to run website from browser until virus files are removed and I managed to collect few strings that ...
1
vote
4answers
3k views

How do you create and execute a bash script which calls an executable from higher folder?

I'm attempting to write a very simple script which calls an executable from a higher level folder. If I were just typing the command into the console, I would type ../filenamehere {options} ...
89
votes
14answers
126k views

How can I resolve a hostname to an IP address in a Bash script?

What's the most concise way to resolve a hostname to an IP address in a Bash script? I'm using Arch Linux.
1
vote
1answer
37 views

How to write a regex to look for strings with fixed length with at least one occurrence of a character

I've been doing some reading on regular expressions and thought I had everything covered, until recently. I've had to filter out all strings of length 5 which end with the letter t and contain at ...
0
votes
1answer
24 views

How to execute several lines into a .txt

I am using SSH; In a folder I have the next files: -rwxrwxr-x 1 german german 48 Apr 29 10:45 prueba.txt -rwxrwxr-x 1 german german 23 Apr 29 10:43 script1.sh -rwxrwxr-x 1 german german 23 Apr ...
0
votes
1answer
41 views

Script for update

I need your help in a script used for update : OLD="int 10" NEW="int 20" i=0 DPATH="/home" for f in $DPATH do sed -i "s/$OLD/$NEW/g" $f let i++ echo "modified:" $f done what i need ...
0
votes
2answers
58 views

How to extract unknown arguments within a shell script?

I have a shell script that accepts a variety of options, some with arguments, some without, some short, some long. It should handle some of these options itself and pass on the rest it does not know ...
1
vote
2answers
40 views

Dynamically create array in bash with variables as array name

This has been asked several times, but none of the methods work. I would like to dynamically create arrays with array names taken from the variables. So lets start with just one array for now: ...
3
votes
2answers
165 views

kill: SIGSTOP: invalid signal specification error in bash script

When I use kill on command line it works. kill -SIGSTOP 1234 But if I use in bash script file I get this error: kill: SIGSTOP: invalid signal specification sh file is #!/bin/sh kill -SIGSTOP ...