The shell is unix's command-line interface. You can type commands in a shell interactively, or write scripts to automate tasks. Use this tag for questions applying to /bin/sh and most compatible shells (ash, bash, ksh, zsh, …).

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3answers
167 views

about executing a python program in a shell script which is scheduled on crontab

i have a problem with regards on crontab. I have a script named checker.sh and i want to schedule it that would run every minute: * * * * * sh /home/pi/checker.sh so i have the script here: the ...
12
votes
5answers
521 views

Find files that contain multiple keywords anywhere in the file

I'm looking for a way to list all files in a directory that contain the full set of keywords I'm seeking, anywhere in the file. So, the keywords need not to appear on the same line. One way to do ...
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0answers
7 views

triggering file transfer with a criteria for time and validity of file with the specific words

i want monitor directoryX/folderA for new files and trigger a copy of all those files that have a specific list of words/ headers in the first line of my file to a different directoryY/folderB . And ...
1
vote
1answer
14 views

Print stderr only if nothing gets written to stdout, otherwise print just stdout discarding stderr

There's a command that always prints stuff to stderr. Such information is never useful except when it doesn't write anything to stdout. So, is there a simple shell way, tool or command to help ...
4
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2answers
8k views

How to grep top most frequent error messages in a unix logfile

If I have a file example apache log file How to extract the top most frequent error messages in a unix log file with no timestamps the key is most frequent error message should come on top of the ...
2
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2answers
36 views

Measure execution time of a command including expansion of command substitution

How would I go about measuring the running time of commands that are expanded by the shell? For example: ➜ time sleep $(sleep 3; echo 1) sleep $(sleep 3; echo 1) 0.00s user 0.00s system 0% cpu 1....
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votes
1answer
41 views

cmd command gives “command line is too long” [on hold]

I wrote a simple bash script, In that script I just execute a .bat file. That .bat file have only 1 command. This command is also not much long. But while I execute my shell script i got "The command ...
0
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0answers
35 views

Run script at startup in linux [on hold]

I want to run my script at startup of my machine and decided to "echo /opt/script/threshold.sh >> /etc/rc.local".I know there are many other ways to do so,Please suggest which one is better and ...
3
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4answers
36k views

Redirecting the content of a file to the command “echo”

I have a file named my_file.txt whose content is just the string Hello. How could I redirect its content to the command echo? I know I have the commands less, cat, more... but I need to do it with ...
1
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1answer
30 views

Initilization script runs twice on SSH

Running Ubuntu 12.04. I have a script that sets up the environment, its run by /etc/bash.bashrc. (It may be set to run by other shell profiles inits, I didn't actually set it up myself) When I Ctr+...
0
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0answers
18 views

find lastly zipped file in a directory which has so many zip files [duplicate]

I am trying to make a script in that i need to execute a command which can give me the lastly zipped logfile(ex:my log file is going to be zipped toady so i need to place this file in script.likewise ...
2
votes
0answers
26 views

Umask value isn't reflected after making changes

I changed umask from 002 to 007 in /etc/bashrc and in /etc/profile. After logging as a normal user I run umask, and it displays 0027. It should display 0007, but it doesn't. What should I do? if [ $...
-1
votes
1answer
29 views

issue while running bash script remotely [on hold]

I created below script to take some backup.When i run it locally or by copying it to remote machine it is running fine. But when i ran it like: ssh asuser@isp2876 "bash -s" -- < AdvanceLog.sh ...
2
votes
2answers
1k views

Trouble with mv and adding the date

I want to be able to move $oldfile to my backup folder and add the date to the file name. So I tried this... mv $oldfile /home/u0146121/backupfiles/$oldfile_$(date +%F-%T) This just gives me this ...
53
votes
6answers
94k views

How can I test if a variable is empty or contains only spaces?

The following bash syntax verifies if param isn't empty: [[ ! -z $param ]] For example: param="" [[ ! -z $param ]] && echo "I am not zero" No output and its fine. But when param ...
9
votes
5answers
8k views

Check if script is started by cron, rather than invoked manually

Is there any variable that cron set when it's running a program ? If the script is running by cron, I'll skip some parts; otherwise invoke those parts. How can I know if the bash script is started by ...
12
votes
4answers
37k views

sudo over ssh: no tty present and no askpass program specified

I keep getting this error and have tried several ways discussed online to fix this and none are working for me. I have setup SSH keys so when I run 'ssh newton@host.com' it automatically logs me in, I ...
1
vote
1answer
33 views

read the file and assign the values to another file

I want to read the file and assign the values to variables whic is in another file using shell script. For example I have file as "myconf" cli="/opt/Solartis_Monitoring/JON_CLI/bin/rhq-cli.sh" user="...
0
votes
1answer
22 views

how to change colors of my ps1 root terminal permanently [duplicate]

I want to change the colors of root@MyComputer:~#and when i type the ls command show me the result as colors! I write a simple BB code to display what i want: [color=red]root@MyComputer:[/color][...
18
votes
3answers
21k views

Is there a simple command for outputting tab-delimited columns?

E.g. I have a file (produced with echo -e "var1\tvar2\t\var3\tvar4" > foo) that are output as: $ cat foo case elems meshing nlsys uniform 2350 0.076662 2.78 non-conformal 348 ...
23
votes
9answers
21k views

How do I check if a variable exists in an 'if' statement?

I need to check a variable's existence in an if statement. Something to the effect of: if [ -v $somevar ] then echo "Variable somevar exists!" else echo "Variable somevar does not exist!" ...
14
votes
2answers
20k views

How do I unset a variable at the command line?

I have tried the following command to set Proxy on yaourt: export ALL_PROXY=http://proxy.example.com:8080 The question is how to unset the proxy on yaourt? In general, how can I unset the value of ...
11
votes
2answers
33k views

How to alter PATH within a shell script?

I have several projects that require me to change versions of Java/Grails/Maven. I'm trying to handle this with some scripts that would make the changes. For example: #!/bin/sh export JAVA_HOME=/...
28
votes
5answers
37k views

Parenthesis in expr arithmetic: 3 * (2 + 1)

expr does not seem to like parenthesis (used in mathematics to explicit operator priority): expr 3 * (2 + 1) bash: syntax error near unexpected token `(' How to express operator priority in bash?
18
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4answers
113k views

how to concatenate string variables into a third?

I need to concatenate two strings in bash, so that: string1=hello string2=world mystring=string1+string2 echo mystring should produce helloworld
10
votes
4answers
372 views

Run command after a certain length of time has elapsed?

If I'm executing a long process, is there any way I can execute some time-based commands? For example, I'm running a really long process which runs for roughly 10 minutes. After 5 minutes, I would ...
1
vote
1answer
174 views

Edit the editor in bash and other shells

Executing the fc builtin causes bash and other shells to fire up $FCEDIT on the last command. Because FCEDIT is a variable, this is inherently customizable. Is it possible to also customize the ...
0
votes
1answer
1k views

openSuse, not running the cron job

I have created a cron job in the /etc/cron.d/dispatchingEmail_I the permissions of dispatchingEmail_I are the following: -rw-r--r-- 1 root root 84 Sep 11 19:52 dispatchingEmail_I content of ...
1
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1answer
19 views

List names of aliases, functions and variables in zsh

I need a way to list the names (without the body/content/value) of aliases, functions, variables, arrays in zsh. Optimally its behave like compgen: compgen -a # will list all the aliases you could ...
1
vote
1answer
48 views

How do I rename files that have '|' in them?

I am using Fedora 24. I have tried many different ways to do this. I've tried it under a Windows VM with the folder in question as a shared folder. I've tried using the 'rename' command. I've ...
1
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1answer
63 views

Why is find not listing matching files when preceded by an asterisk(*)? [duplicate]

On Ubuntu 14.04, 64 bit, I have set /lib/modules/4.2.0-27-generic/kernel/drivers to be my current directory. I intend to search all files having net present as a sub-string. If I search with a regex ...
0
votes
2answers
62 views

How do I record all terminal input and output to a local file by default for each session?

I'm aware the script command can be used to record all keyboard input and screen output to a file, but this has to be invoked each time a terminal session is started. I keep timestamped versions of my ...
1
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0answers
35 views

unable to set GOPATH, but it is set? [on hold]

I cannot set $GOPATH, no matter what! I ran: mkdir ~/HOME/myGOfolder And also copied these two commands to ~/.bashrc and ~/.profile (just in case): export GOPATH="$HOME/myGOfolder" export PATH=$...
2
votes
1answer
43 views

How can I decompress and print the last few lines of a compressed text file?

I have 6 gzipped text files, each of which is ~17G when compressed. I need to see the last few lines (decompressed) of each file to check whether a particular problem is there. The obvious approach is ...
0
votes
2answers
55 views

Why is the default shell on my Ubuntu 14.04 bash?

Some said that Ubuntu 14.04's default shell is dash. Mine is bash. My /bin/sh is dash. I don't remember if I changed the default shell. What is some way to change the default shell? Can I find out ...
3
votes
2answers
68 views

confused with awk and shell variables

I am trying to run a script that uses awk. There is no error it seems, but it doesn't create the file that I want. This is the script: #!/bin/bash echo "Number of domain:" read number echo "Domain ...
-1
votes
1answer
43 views

for loop # usage

I am trying to understand how this piece of code works: for b in `git branch -r`; do git branch --track ${b##upstream/} $b; done In particular, the part where it does ${b##upstream/} I know it ...
2
votes
2answers
148 views

Play subtitles automatically with mpv

Subtitle files come in a variety of formats, from .srt to .sub to .ass and so on and so forth. Is there a way to tell mpv to search for subtitle files alongwith the media files and if it does to start ...
7
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4answers
1k views
59
votes
5answers
76k views

What does ` (backquote/backtick) mean in commands?

I came across the following command: sudo chown `id -u` /somedir and I wonder: what is the meaning of the ` symbol. I noticed for instance that while the command above works well, the one below ...
22
votes
1answer
2k views

Is there a way to redirect a program's output and still have it go to stdout?

Okay. If I wanted to redirect the output of a program to a file, I'd do something like this prog > file If I wanted to redirect both stdout and stderr to that file, then I'd do prog > file 2&...
4
votes
5answers
1k views

List files with line count and date

I want to be able to list files showing the number of lines the each file has and the date. I can happily get the line count using wc -l *. Not a problem. I can get the date using ls -l. Is there a ...
2
votes
2answers
53 views

Pass input file through pipe as argument?

I have two issues. I am trying to pass files through a pipe as an argument, and I am trying to use that file as a variable inside the sh function. Here is my command: find . -name 'segment*' | ...
1
vote
1answer
36 views

Formatting issue

I have a small script like below, where output gets highlighted (in red,yellow etc) on screen if there an issue normal=$(tput sgr0) red=$(tput setaf 1) yellow=$(tput setaf 3) df -h >/dev/null 2&...
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votes
2answers
35 views

Add another if condition

The following script is working fine. for i in `cat /app/scripts/symantec_scripts/list` do ssh root@$i "uname -n if [ -s /app/Symantec/virusdefs/definfo.dat ]; then cat /app/Symantec/virusdefs/...
0
votes
3answers
96 views

shell script - subtract 1 from hexadecimal mac address and add colons to it

I have mac address as 'C4:B9:83:7F:FF:AC' and I want to subtract 1 from its hex values which is C4B9837FFFAC so it will become C4B9837FFFAB and after this I again want to add colons to make it ...
-2
votes
2answers
9k views

How to delete a file in Arch console?

pacman stopped working and asked me to delete a file if "another package manager isn't working". What is the file for deleting files?
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votes
2answers
132 views

z in bash script returns zero [closed]

#[ -z "" ] #echo $? returns 0 #[ -a "" ] #echo $? returns 1 except z all other alphabets throw 1 What might be the reason?
10
votes
2answers
12k views

Printing decimal to ascii character, my command does not output as intended

I wanted to output a string of all the ascii characters with the following command for i in `seq 32 127`; do printf "%c" $i; done The output of the above command is: ...
14
votes
4answers
1k 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 ...