Why does my sequence result in "syntax error near unexpected token"?

Question

I have written this code to ping multiple IP addresses but it does not work. Can anyone please tell me what's wrong here?

#!/bin/bash
for i in 'seq 1 20' do  
    ping -c 1 "10.88.209.$i";
done

ps: the error it is showing is => ./ping.sh: line 3: syntax error near unexpected token ping' ./ping.sh: line 3: ping -c 1 "10.88.209.$i";'

backticks around the command and a semicolon before the do : `for i in \`seq 1 20\`; do ..` — amdixon, Aug 23 '15 at 06:07
See: http://stackoverflow.com/questions/32163619/whats-the-difference-between-and-in-bash — Cyrus, Aug 23 '15 at 06:08
./ping.sh: line 4: syntax error near unexpected token `ping' ./ping.sh: line 4: ` ping -c 1 "10.88.209.$i";' this is the error it is showing — Rishabh Gour, Aug 23 '15 at 06:09
Add a `;` before `do`. Take a look at: http://www.shellcheck.net/ — Cyrus, Aug 23 '15 at 06:12

score 3 · Answer 1 · answered Aug 23 '15 at 06:11

3

Use:

for i in $(seq 1 20); do

or

for i in {1..20}; do

or

for ((i=0;i<=20;i++)); do

obsolete:

for i in `seq 1 20`; do

answered Aug 23 '15 at 06:11

Cyrus

84,225
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Why the last one is obsolete? – higuaro Aug 23 '15 at 06:43
Please see slm's detailed posting at [Unix & Linux](http://unix.stackexchange.com/a/126928/74329) to this topic. – Cyrus Aug 23 '15 at 06:51

Todd A. Jacobs · Accepted Answer · 2015-08-23T06:16:30.293

Your syntax is broken. Single quotes and back-ticks are not interchangeable, and for-loops require a semicolon or newline before the do keyword. For example:

#!/usr/bin/env bash

for i in `seq 1 20`; do
    ping -c 1 "10.88.209.${i}"
done

Rather than spawning seq, you can also use the more efficient (and more idiomatic) Bash brace-expansion sequence. For example:

#!/usr/bin/env bash

for i in {1..20}; do
    ping -c 1 "10.88.209.${i}"
done

Why does my sequence result in "syntax error near unexpected token"?

2 Answers2