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123
votes
5answers
38k views

Why is printf better than echo?

I have heard that printf is better than echo and I can recall only one instance from my experience where I had to use printf because echo didn't work for feeding some text into some program on RHEL ...
82
votes
3answers
7k views

Why is “echo” so much faster than “touch”?

I'm trying to update the timestamp to the current time on all of the xml files in my directory (recursively). I'm using Mac OSX 10.8.5. On about 300,000 files, the following echo command takes 10 ...
23
votes
4answers
4k views

How to echo a bang!

I tried to create a script by echo'ing the contents into a file, instead of opening it with a editor echo -e "#!/bin/bash \n /usr/bin/command args" > .scripts/command The output: bash: ...
23
votes
1answer
955 views

Why does echo >file use more real time than echo | sed >file?

The example, below, surprised me. It seems to be counter intuitive... aside from the fact that there is a whisker more user time for the echo | sed combo. Why is echo using so much sys time when it ...
13
votes
4answers
9k views

How to delete line with echo?

I know that I could delete the last three chars with: echo -ne '\b\b\b' But how can I delete a full line? I mean I dont want to use: echo -ne ...
9
votes
2answers
1k views

Using sed to color the output from a command on solaris

I have a ksh script that must work on both linux and solaris. I'm trying to color the output of specific commands. It works on linux (specifically RHEL6), but not on solaris (SunOS 5.10). Command ...
7
votes
7answers
1k views

timestamp before an echo

Exists a nicer way to create timestamp in front of an echo? Currently I do it this way: #!/bin/sh if mount | grep -q /mnt/usb; then echo `date +%R\ ` "usb device already mounted" else ...
7
votes
4answers
3k views

How can I create a file with multiple lines from the command-line?

How can I enter the following contents in a file: Hi abcd I tried using echo "Hi\nabcd" >> ab.txt, but in the file it's written as is (the \n is included, instead of a newline)
7
votes
1answer
692 views

Append same text to many files using cat or echo?

How can I write the same content to many text files by using cat or echo in only one command? For example I want to write "hello" to file1 and file2. I tried: echo "hello" >> file1 file2 ...
7
votes
3answers
329 views

What defines the maximum size for a command single argument?

I was under the impression that the maximum length of a single argument was not the problem here so much as the total size of the overall argument array plus the size of the environment, which is ...
6
votes
3answers
2k views

Escape sequences with “echo -e” in different shells

I just noticed that it seems like the flag -e does not exist for the echo command in my shell on Linux. Is this just a messed up setting or is it "normal"? Some code as an example: #!/bin/sh echo -e ...
6
votes
4answers
484 views

What is the difference between echo `date`, echo “`date`”, and echo '`date`'?

What is the difference between these three commands? echo `date` echo "`date`" echo '`date`' I am confused on what the differences actually are. I think that when the ' are around it means that it ...
6
votes
3answers
14k views

How do I set an environment variable on the command line and have it appear in commands?

If I run export TEST=foo echo $TEST It outputs foo. If I run TEST=foo echo $TEST It does not. How can I get this functionality without using export or a script?
6
votes
3answers
263 views

adding an empty first line inside csv file

I input data into a csv by 'echo'-ing some values into another csv. I tried echo "" and in the next line echo "values" but i get intermittent empty lines.. I need empty line only at the start....
6
votes
1answer
341 views

differences between echo“”> and > command

I am new to Linux. There is something that is unclear to me. What is the difference between echo "" > logfile and > logfile ? When I run the first one, the logfile size doesn't become zero ...
6
votes
4answers
11k views

printing colored text using echo

I know that for printing a colored text using echo, for example red color, the code is: echo -e "\e[1;31m This is red text \e[0m" and I know that in this example, 31 is code of red color and the ...
6
votes
2answers
4k views

Unexpected results testing serial loopback using echo and cat

So I have a standard RS232 serial port that is looped back to itself by simply running a wire from Tx to Rx. I'm testing loopback by running echo and cat in two separate terminals: cat /dev/ttyS1 ...
5
votes
2answers
354 views

Quoted vs unquoted string expansion

for i in $(xrandr); do echo "$i" ; done for i in "$(xrandr)"; do echo "$i"; done for i in "$(xrandr)"; do echo $i; done I understand why 1 differs from 2. But why does 3 give a different output ...
5
votes
2answers
385 views

Unix: how to read line's original content from file

I have a data file, the content is as follows: department: customer service section: A department: marketing section: A department: finance section: A When I read each line, I ...
5
votes
3answers
534 views

Construct a command by putting a string into a tty

I managed to do this echo -n "command" > /dev/tty1 The letters appear, and the cursor moves, but they are "ghosts" - if you hit enter, nothing happens (they are not in stdin). Edit: In the ...
4
votes
4answers
7k views

Why is echo ignoring my quote characters?

The echo command isn't including the complete text that I give it. For example, if I do: $ echo ' echo PARAM=` grep $ARG /var/tmp/setfile | awk '{print $2}' ` ' It outputs: echo PARAM=` ...
4
votes
2answers
294 views

Why am I observing different behaviour of echo?

I am a bash beginner and observed the below behavior of echo #!/bin/bash x=" hello" echo $x echo "$x" Now when I run the above code I get ronnie@ronnie:~$ bash test.sh hello hello ...
4
votes
4answers
355 views

Bash Scripting : Printing column data in the same row

I have written a bash script to calculate the size of a PostgreSQL database and print the output along with the date when the script was executed in a text file. The script code is as follows: ...
4
votes
1answer
194 views

Ubuntu unattended install : echo keypress to dialog

Ubuntu 12.04 LTS Server 64 My unattended-mode bootstrap.sh script contains: apt-get upgrade -y I know that during execution a primitive UI for GRUB installation will be shown which requires ...
3
votes
2answers
318 views

Weird output by echo

I was playing with echo $$ a while back. Well that displays that pid of the shell. But then I did echo ! which promptly displayed !. Then echo !! produced echo echo ! echo ! $echo !!! gave echo ...
3
votes
1answer
107 views

Why doesn't text piped into an echo get outputted?

Why doesn't this command output "1"? echo 1 | echo I imagine it working this way: 1. echo 1 (outputs 1) 2. | echo (takes the 1 as an input, then echos it) Isn't this what should happen?
3
votes
4answers
142 views

How can I print “-n” with `echo`?

I feel really stupid, yet I can't figure how to print the string "-n" with the over 30 years-old command echo. I tried these: Michaels:Scripts$ echo -n Michaels:Scripts$ echo "-n" Michaels:Scripts$ ...
3
votes
3answers
148 views

Split a returned block of text into lines in terminal?

When I give commands like echo $PATH or which program, I often get a very large block of text consisting of may directories. This is fairly useless, if I am for example, looking to see if there is or ...
3
votes
2answers
86 views

Command in variable one are affecting output of other variable when displayed together in UNIX

I am having two file naming Extra_info and Class_info Class_info contains data : stuId stuName stuClass S01 jagdeep First S02 harsh First S03 Roop Second S04 Kali Third ...
3
votes
2answers
425 views

print command instead of echo in linux

I simply can print a message in terminal using linux echo command. prayag@prayag$ echo "prayag works on JVM" prayag works on JVM Can I have the same output with print command. I actually went ...
3
votes
2answers
147 views

How do I echo an expression with both single and double quotes?

I have tried many things, but I'm new to the shell. Is it possible to have both double and single quotes within an echo? I want to generate echo "scan 'LPV',{FILTER => "(PrefixFilter ...
3
votes
1answer
318 views

Shell script doesn't paint last line of stdout to screen without user input

I have a shell script that's happily doing all my backup process and writing progress to stderr and stdout, with one exception — the last line doesn't get written to my terminal (if I call the script ...
3
votes
1answer
196 views

Prevent hanging of “echo STRING > fifo” when nothing is reading that FIFO

When I echo something to a named pipe made with mkfifo, it hangs if no process is reading from that pipe. How can I prevent that, i.e., stop that from hanging? And by the way, why is that hanging ...
3
votes
2answers
193 views

insert text in a file using echo command [duplicate]

I am trying to insert some text in a file in the following way sudo echo "abc-abc/abc/abc" >> /etc/portage/make.conf but it give me the error Permission denied although I am using sudo ...
3
votes
1answer
459 views

Printing colored text using script

When I type below command in the shell I get the OUTPUT in green color. Command echo "\033[32mCONNECTING TO abpwrk\033[m"; Output(in green color) CONNECTING TO abpwrk But if I use the same ...
3
votes
2answers
253 views

echo string >> file does not work

I wrote the following script: for filename in `find . -name '*'.cpp | grep $IN_REGEX | grep -v $OUT_REGEX` do echo "Output file is $OUTPUT_FILE" count=`git log --pretty=format: --name-only ...
3
votes
0answers
156 views

How to create a bash command which creates output that exactly mimics a source text file that can be pasted into bash shell where histexpand is on?

The goal is to create a bash one line command that can be copied and pasted - for instance published on a web forum - and then patches files. See it as a way to distribute a patch file by copy and ...
2
votes
3answers
496 views

How to stop `grep` from truncating pipe output

Is there any way to have an echo at the end of a pipe simply append to the current output rather than removing it all? For example, how can I keep the output for my cat and grep and add "END OF ...
2
votes
1answer
227 views

My echo command doesn't accept switches (echo -n or echo -e)

I have an echo statement in my script as below: echo -ne "Check Script"; I was expecting it to print Check Script but I am getting the below output -ne Check Script But when I run the same ...
2
votes
1answer
75 views

'echo' eats part of the message

I want to write a script that will dump all partitions of my android device through the android debug bridge and since this is a time intensive process I want to notify the user about the progress by ...
2
votes
2answers
4k views

How can I trim the carriage return from text that is being piped in bash?

I'm using this command to get my last typed command: history | cut -c 8- | tail -n 2 | head -n 1 It works very well in bash, removing the line numbers, but there is one problem I have with it, (er, ...
2
votes
1answer
271 views

How to echo in shell script without executing the result

I am using this code to print all open files in the specified changelist. while read line; do echo "$line" done < `p4 opened -c $changelist` However, the line also gets executed and I get ...
2
votes
1answer
74 views

How to use OSLEC with Alsa as default, not with Pulseaudio or other thirdparty package involved?

Oslec Echo canceller I have seen some packages used OSLEC and there echo cancle was very well. So for a test simulation, how could i install the OSLEC only with Alsa (i do not use PulseAudio at all, ...
1
vote
2answers
1k views

Alias Loop in csh

Why is there an Alias loop error created here: alias df 'printf "\n"; df -hP | column -t' But not here: alias df 'df -hP | column -t' I realize I could call the alias something else and still ...
1
vote
2answers
506 views

How can I right-justify variable length output?

So I don't want this: echo "9" 9 Rather I need this, with e.g.: 4 spaces before it: MAGICK "9" 9 So if I try it with 10: MAGICK "10" 10 then it will just have 3 spaces before it. How ...
1
vote
3answers
232 views

Is there any alternative to echo daemon to display ip?

Is there any alternative to echo daemon to display ip instead of given string? For ex: my ip = 80.1.2.3 server ip = 1.2.3.4 root@my-machine bash$ telnet 1.2.3.4 Trying 1.2.3.4... Connected to ...
1
vote
2answers
160 views

Why the inconsistency with using cat vs. echo piped to this sed command?

Inspired by this question: sed: N command does not read single line I wanted to understand why there appears to be an inconsistency between the following 2 commands: #1. echo This command produces ...
1
vote
2answers
160 views

How to make sure the shell builtin echo is invoked so that its not visible in process list?

Is this going to be visible in the process listing if the below line is executed from a command line or a shell script bash -c "echo $password" or i just need to do echo $password from within ...
1
vote
1answer
49 views

Netcat (nc6) - Minimal IPv6 only TCP Server and Client

Im am trying to set up a basic IPv6 only echo-server using netcat (or rather nc6). Client and server are both in the same local network. However, the client quits immediately: IPv6-Server: $ nc6 ...
1
vote
2answers
1k views

Print line numbers of files I am searching through [closed]

I am looking for a way to print the line number of files my script is going through. I have found $LINENO but when I do echo 'Found foo in file' $(basename $foo) 'on line' $LINENO >> foo.csv ...