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
435 views

linux + awk + file manipulation

I have the following file more file.txt 1 2 3 4 4 2 23 4 5 23 2 3 END_OF_LINE 1 3 7 4 2 23 4 6 7 4 2 1 5 How to print only the fields 4 and 5 and 6 until the line END_OF_LINE , and from ...
25
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3answers
10k views

How do you process an entire command as sudo that involves redirecting or piping?

I am trying to follow what I assume is best practises of using sudo instead of root account. I am running a simple concat file operation such as: sudo echo 'clock_hctosys="YES"' >> ...
11
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3answers
16k views

How to add a function to .bash_profile/.profile/bashrc in shell?

I have a function which converts epoch time to date. Here is the definition date1(){ date -d @$1 } I'd like to be able to write: $ date1 xxxyyy Where xxxyyy is the parameter I pass into my ...
2
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4answers
5k views

How to check the process along with its arguments in process list?

I have written a script where i need to pass several arguments with the same script, the script is being executed after a certain time using cron. In order to make sure that there are no multiple ...
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2answers
125 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?
0
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1answer
653 views

How to write conditional if statement in bash shell script?

I have a below shell script which will get the latest folder from my current directory in machineB and machineC. So I came up with the below command which will find me the latest folder inside - ...
2
votes
2answers
328 views

How to cd into a directory as part of shell script and do a word count of files?

I am trying to get the latest folder inside my directory in machineB and machineC. So I came up with the below command which will find me the latest folder inside - `/bat/data/snapshot` And that ...
1
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2answers
74 views

Running a program to output in Dutch

I'm running KDE Arch linux and trying to update my system using pacman and have it output in Dutch. I've tried the following sudo LANG=nl_NL.UTF-8 pacman -Syy sudo KDE_LANG=nl_NL.UTF-8 pacman -Syy ...
1
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3answers
228 views

How do I iterate the list and copy the files from machineB and machineC efficiently?

I need to scp the files from machineB and machineC to machineA. I am running my below shell script from machineA. I have setup the ssh keys properly. If the files are not there in machineB, then it ...
0
votes
2answers
247 views

zsh: What does the command “time + number” do in zsh

When I type time + number in zsh: # atupal at local in /tmp/atupal/setup/bin [10:01:49] $ time 1 /tmp/atupal/setup/bin/lib/python2.7 # atupal at local in /tmp/atupal/setup/bin/lib/python2.7 ...
3
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3answers
145 views

capture output from command without interference

How can I test whether a command's output is an empty string without interfering with said output? Example: command | ??? if [ $? = 0 ] && [ -n "$output_from_command"]; then ... I'd ...
2
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3answers
1k views

awk print ' char

I want to print: cat file.log | awk '{print nir's $1}' output should be: nir's aaa nir's bbb nir's abc nir's dbc The problem is with the ' in nir's. I also tried: cat file.log | awk '{print ...
2
votes
3answers
7k views

Copy files from a list to a folder

I have a text file abc.txt and its contents are: /lag/cnn/org/one.txt /lag/cnn/org/two.txt /lag/cnn/org/three.txt If I use: $ tar -cvf allfiles.tar -T abc.txt I'm getting the tar of ...
9
votes
2answers
9k views

Is there any way to use xargs across a pipe?

I'm trying to automatically convert flac files moved to a folder into mp3 in another folder. My current line of code is this: inotifywait -m -r -q -e moved_to --format "'%w%f'" ~/test | xargs -I x ...
2
votes
2answers
356 views

Pipeline with grep and find prints numbers infront of result

Am using the following "find" command to extract some files, find /lag/cnnf/ -maxdepth 3 -newer ./start ! -newer ./end | grep -nri abc | egrep '([^0-9]45[^0-9])' | grep -nri "db.tar.gz" >> ...
2
votes
1answer
731 views

Command not found in zsh [duplicate]

In bash, whenever I try to run a command which is not installed, I get a message which tells that the package is not installed and how to install it. This functionality is provided by installing the ...
9
votes
3answers
2k views

Why does the less-than sign not work as a replacement for cat in bash?

I heard about "useless use of cat" and found some suggestions, but the following outputs nothing in my bash shell. < filename Using cat works as expected though. cat filename I'm using Fedora ...
1
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3answers
314 views

the difference between '..' and “..” when I use ssh usr@ip 'pscp …'

My Server machine run Window,and it installed Cygwin. My Client machine run linux. In Clinent machine.I do this: [sikaiwei@login-1-2 v1.4]$ bash test.sh CHUN~19900405 ...
2
votes
1answer
420 views

what is wrong with this command? [closed]

I have this command in a shell script. I this command I am connecting to ftp server and reading a file path/download.txt to read further commands. sftp -v -oIdentityFile=/root/.ssh/filename ...
4
votes
1answer
712 views

Which 2-letter POSIX command is different from all the others?

I was interviewed for an internship and I got the same question as this one: http://www.glassdoor.com/Interview/Which-2-letter-POSIX-command-is-different-from-all-the-others-QTN_498236.htm The ...
5
votes
1answer
448 views

Replace CD number in MP3 ID3 tag

I have a library of MP3 files where in some files the "CD number" tag (TPOS) contains "CDx" values, e.g. "CD1" or "CD2". The ID3 spec says that TPOS values shall be numerical strings. Processing these ...
11
votes
2answers
307 views

Output order with process substitution

This is what I usually do to run grep and wc on a file without having to scan it twice <file.txt tee >(grep LITERAL) >(wc -l) >/dev/null However, this yields EXEC LITERAL 32 ...
25
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3answers
5k views

What does “rm is hashed” mean?

I'm going through http://mywiki.wooledge.org/BashGuide/CommandsAndArguments and came across this: $ type rm rm is hashed (/bin/rm) $ type cd cd is a shell builtin Just a little earlier, the guide ...
2
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2answers
2k views

Busybox ash script does not exit cleanly after executing cat; unable to get exit code

Consider the following script wrapcat.sh (a wrapper for cat) for illustrative purposes. It is run with busybox (ash) in an embedded Linux 2.6 box. #!/bin/sh cat $1 Under certain circumstances, this ...
1
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1answer
189 views

How to script this task?

First of all, I can make basic use of the linux command line, but have slim to none experience with shell scripting. What I want to do: I have a router running OpenWRT, a destop pc and an Android ...
19
votes
9answers
5k views

Grep lines but let the first line through [duplicate]

Consider the following output from df. Filesystem Size Used Avail Use% Mounted on /dev/sda1 23G 6.1G 16G 29% / udev 10M 0 10M 0% /dev tmpfs 397M 420K ...
7
votes
4answers
405 views

Prevent terminal from displaying previously executed command

I have a script that allows me to log random thoughts while working on a project. In the terminal I would add a new log entry by running $ @ "some random thought" where @ is just an alias for my ...
10
votes
2answers
2k views

How does GLOBIGNORE work?

According to bash's manual page: GLOBIGNORE A colon-separated list of patterns defining the set of filenames to be ignored by pathname expansion. If a filename matched by a ...
3
votes
1answer
300 views

Read the files in shell script doesn't print out anything?

I am trying to read a file from shell script line by line. Below is my file content - hello=world And below is my shell script that I have written - #!/bin/bash while read -r line; do ...
5
votes
5answers
6k views

How to search in specific files matching a pattern

How can I find a word in specific files matching a pattern. e.g. searching for version in CMake* files recursively found in the current directory.
7
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3answers
3k views

ImageMagick on multiple files

I have converted a single file from BMP to PNG with ImageMagick's convert using the command below convert CD\ Front.bmp CD\ Front.png I have many such files, thus I tried: for f in */*.bmp ; do ...
1
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3answers
648 views

Quoting in command substitution

The command pdftk FileOne.pdf "File two.pdf" output Combined.pdf works as expected, merging PDF's One and Two. However, if I put the filenames in a file FileOne.pdf "File Two.pdf" and ...
3
votes
3answers
3k views

How to move the first x files

I have this huge folder with thousands of unordered files. Is it feasible to move the first 5000s to a subfolder via the mv command? For now I move files with mv *some_pattern* ./subfolder1/ ...
18
votes
1answer
5k views

GNU parallel vs & (I mean background) vs xargs -P

I'm confused about the difference or advantage (if any) of running a set of tasks in a .sh script using GNU parallel E.g. Ole Tange's answer: parallel ./pngout -s0 {} R{} ::: *.png rather than say ...
2
votes
1answer
126 views

“No such file” warning on terminal launch

I ran a source command on a file that was missing. I forgot about it but later noticed that every time I opened a new terminal, the first line would be a warning about the missing file bash: ...
1
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2answers
140 views

Removing “[crap-like-this]” from strings using bash parameter expansion?

If I have the following $STRING aaa.bbb.ccc.[ddd].eee.fff.[ggg].hhh is there any way, using bash parameter expansion, to echo the following aaa.bbb..ccc.eee.fff..hhh That is, remove all ...
0
votes
1answer
126 views

Could not get a command to work with bash -c

I am trying to execute a command to find out which process is listening on a particular port and i cannot get it to work if the command is passed as an argument to bash using bash -c netstat -tnlp ...
25
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3answers
3k views

Multicolored Grep

I'm trying to get each grep command to highlight it's results in a different color. I can do it manually with a line like this: ls -l GREP_COLORS='mt=01;32' grep c | GREP_COLORS='mt=01;31' grep o | ...
2
votes
1answer
362 views

How to avoid sending EOF from a script parsing requests from and sending answers to netcat

I made a simple server using netcat and backpipe: mkfifo backpipe nc -l 8080 < backpipe | parseRequests.sh > backpipe The contents of "parseRequests.sh" is just: #!/bin/sh if [ "$1" = "1+1" ...
24
votes
2answers
5k views

What is the difference between shell, eshell, and term in Emacs?

In Emacs I can run a shell using following commands - M-x term M-x shell M-x eshell What is the difference between these three?
19
votes
3answers
811 views

Use of ^ as a shell metacharacter

I wrote a small script today which contained grep -q ^local0 /etc/syslog.conf During review, a coworker suggested that ^local0 be quoted because ^ means "pipe" in the Bourne shell. Surprised by ...
1
vote
1answer
292 views

Cat write text with “$” inside

I want to write configuration information to a specific file which has dollar signs ($) inside. That seems to be a problem. Here's what I did: $ cat >> /etc/nginx/nginx.conf <<EOF # For ...
2
votes
1answer
393 views

Send keystrokes to a process on Console

If I have a terminal with a shell open, how can I write a shell script (any scripting language is ok with me!) that will send a keystroke to any one of the running processes? As an example, how could ...
1
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3answers
615 views

Prevent wildcard expansion on find

Is there a way to prevent wildcard expansion on the find command so that the following would work? find . -iname "foo [bar]" As pointed out here, I tried running set -f, set -o noglob and setopt ...
0
votes
1answer
724 views

&> redirection not working correctly

Please see the following shell transcript: $ ls input.txt test-amp-gt.sh test-both-2.sh test-both.sh test-gt.sh $ cat input.txt input file $ cat test-gt.sh #! /bin/sh cat input.txt > ...
1
vote
1answer
125 views

Can I increase brightness of text in Arch shell?

I just installed Arch Linux. All I have right now is the shell. The text is very difficult to read on a black background. My eyesight is fine. Can I change the brightness of the text, or can I ...
3
votes
3answers
220 views

Print a message from the left-hand side of a pipe

I want to use a variable from the main shell in a sub shell. I did: export mysql_root_password="test" ( echo $mysql_root_password ) | dialog --gauge "Working hard..." 6 50 There is no output. ...
0
votes
2answers
97 views

What's the difference of get command output using`command`and $(command) in Shell? [duplicate]

What is the difference in collect a command output in Shell script using `command` and $(command)? For example: # IP1=$(ifconfig eth0 | grep -e "inet " | cut -d: -f2 | awk '{print $1}') # ...
-1
votes
2answers
73 views

How can I delete a file on client?

After copying files from /home/foo/bar the original files on the client must be deleted, EXCEPT for file /home/foo/bar/special_file. This file must remain on the client. I want to delete all the files ...
0
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2answers
14k views

How to copy only the files of a folder(including subfolder's files), but not the folder itself in shell

In Openssh, On the client, the content of path/to/file must be copied to Server. All files in /path/to/file on the client must be copied to /path/to/files on the server. Note: only copy files, no ...